The obvious issue here is that log_bin_trust_function_creators isn't an available parameter for the sqlserver-se-12.0 parameter group family as you can see here when listing all the parameters in a parameter group based on sqlserver-se-12.0:
$ aws rds describe-db-parameters --db-parameter-group-name test-sqlserver-se-12-0 --query 'Parameters[*].ParameterName'
[
"1204",
"1211",
"1222",
"1224",
"2528",
"3205",
"3226",
"3625",
"4199",
"4616",
"6527",
"7806",
"access check cache bucket count",
"access check cache quota",
"ad hoc distributed queries",
"affinity i/o mask",
"affinity mask",
"agent xps",
"allow updates",
"backup compression default",
"blocked process threshold (s)",
"c2 audit mode",
"clr enabled",
"contained database authentication",
"cost threshold for parallelism",
"cross db ownership chaining",
"cursor threshold",
"database mail xps",
"default full-text language",
"default language",
"default trace enabled",
"disallow results from triggers",
"filestream access level",
"fill factor (%)",
"ft crawl bandwidth (max)",
"ft crawl bandwidth (min)",
"ft notify bandwidth (max)",
"ft notify bandwidth (min)",
"in-doubt xact resolution",
"index create memory (kb)",
"lightweight pooling",
"locks",
"max degree of parallelism",
"max full-text crawl range",
"max server memory (mb)",
"max text repl size (b)",
"max worker threads",
"media retention",
"min memory per query (kb)",
"min server memory (mb)",
"nested triggers",
"network packet size (b)",
"ole automation procedures",
"open objects",
"optimize for ad hoc workloads",
"ph timeout (s)",
"priority boost",
"query governor cost limit",
"query wait (s)",
"recovery interval (min)",
"remote access",
"remote admin connections",
"remote login timeout (s)",
"remote proc trans",
"remote query timeout (s)",
"replication xps",
"scan for startup procs",
"server trigger recursion",
"set working set size",
"show advanced options",
"smo and dmo xps",
"transform noise words",
"two digit year cutoff",
"user connections",
"user options",
"xp_cmdshell"
]
Instead that parameter is only available in MySQL flavours:
$ aws rds describe-db-parameters --db-parameter-group-name default.mysql5.6 --query 'Parameters[*].ParameterName'
[
"allow-suspicious-udfs",
"auto_increment_increment",
"auto_increment_offset",
"autocommit",
"automatic_sp_privileges",
"back_log",
"basedir",
"binlog_cache_size",
"binlog_checksum",
"binlog_error_action",
"binlog_format",
"binlog_max_flush_queue_time",
"binlog_order_commits",
"binlog_row_image",
"binlog_rows_query_log_events",
"binlog_stmt_cache_size",
"binlogging_impossible_mode",
"bulk_insert_buffer_size",
"character-set-client-handshake",
"character_set_client",
"character_set_connection",
"character_set_database",
"character_set_filesystem",
"character_set_results",
"character_set_server",
"collation_connection",
"collation_server",
"completion_type",
"concurrent_insert",
"connect_timeout",
"core-file",
"datadir",
"default_storage_engine",
"default_time_zone",
"default_tmp_storage_engine",
"default_week_format",
"delay_key_write",
"delayed_insert_limit",
"delayed_insert_timeout",
"delayed_queue_size",
"div_precision_increment",
"end_markers_in_json",
"enforce_gtid_consistency",
"eq_range_index_dive_limit",
"event_scheduler",
"explicit_defaults_for_timestamp",
"flush",
"flush_time",
"ft_boolean_syntax",
"ft_max_word_len",
"ft_min_word_len",
"ft_query_expansion_limit",
"ft_stopword_file",
"general_log",
"general_log_file",
"group_concat_max_len",
"gtid-mode",
"host_cache_size",
"init_connect",
"innodb_adaptive_flushing",
"innodb_adaptive_flushing_lwm",
"innodb_adaptive_hash_index",
"innodb_adaptive_max_sleep_delay",
"innodb_autoextend_increment",
"innodb_autoinc_lock_mode",
"innodb_buffer_pool_dump_at_shutdown",
"innodb_buffer_pool_dump_now",
"innodb_buffer_pool_filename",
"innodb_buffer_pool_instances",
"innodb_buffer_pool_load_abort",
"innodb_buffer_pool_load_at_startup",
"innodb_buffer_pool_load_now",
"innodb_buffer_pool_size",
"innodb_change_buffer_max_size",
"innodb_change_buffering",
"innodb_checksum_algorithm",
"innodb_cmp_per_index_enabled",
"innodb_commit_concurrency",
"innodb_compression_failure_threshold_pct",
"innodb_compression_level",
"innodb_compression_pad_pct_max",
"innodb_concurrency_tickets",
"innodb_data_home_dir",
"innodb_fast_shutdown",
"innodb_file_format",
"innodb_file_per_table",
"innodb_flush_log_at_timeout",
"innodb_flush_log_at_trx_commit",
"innodb_flush_method",
"innodb_flush_neighbors",
"innodb_flushing_avg_loops",
"innodb_force_load_corrupted",
"innodb_ft_aux_table",
"innodb_ft_cache_size",
"innodb_ft_enable_stopword",
"innodb_ft_max_token_size",
"innodb_ft_min_token_size",
"innodb_ft_num_word_optimize",
"innodb_ft_result_cache_limit",
"innodb_ft_server_stopword_table",
"innodb_ft_sort_pll_degree",
"innodb_ft_user_stopword_table",
"innodb_io_capacity",
"innodb_io_capacity_max",
"innodb_large_prefix",
"innodb_lock_wait_timeout",
"innodb_log_buffer_size",
"innodb_log_compressed_pages",
"innodb_log_file_size",
"innodb_log_group_home_dir",
"innodb_lru_scan_depth",
"innodb_max_dirty_pages_pct",
"innodb_max_purge_lag",
"innodb_max_purge_lag_delay",
"innodb_monitor_disable",
"innodb_monitor_enable",
"innodb_monitor_reset",
"innodb_monitor_reset_all",
"innodb_old_blocks_pct",
"innodb_old_blocks_time",
"innodb_online_alter_log_max_size",
"innodb_open_files",
"innodb_optimize_fulltext_only",
"innodb_page_size",
"innodb_print_all_deadlocks",
"innodb_purge_batch_size",
"innodb_purge_threads",
"innodb_random_read_ahead",
"innodb_read_ahead_threshold",
"innodb_read_io_threads",
"innodb_read_only",
"innodb_replication_delay",
"innodb_rollback_on_timeout",
"innodb_rollback_segments",
"innodb_sort_buffer_size",
"innodb_spin_wait_delay",
"innodb_stats_auto_recalc",
"innodb_stats_method",
"innodb_stats_on_metadata",
"innodb_stats_persistent",
"innodb_stats_persistent_sample_pages",
"innodb_stats_transient_sample_pages",
"innodb_strict_mode",
"innodb_support_xa",
"innodb_sync_array_size",
"innodb_sync_spin_loops",
"innodb_table_locks",
"innodb_thread_concurrency",
"innodb_thread_sleep_delay",
"innodb_undo_directory",
"innodb_undo_logs",
"innodb_undo_tablespaces",
"innodb_use_native_aio",
"innodb_write_io_threads",
"interactive_timeout",
"join_buffer_size",
"keep_files_on_create",
"key_buffer_size",
"key_cache_age_threshold",
"key_cache_block_size",
"key_cache_division_limit",
"lc_time_names",
"local_infile",
"lock_wait_timeout",
"log-bin",
"log_bin_trust_function_creators",
"log_bin_use_v1_row_events",
"log_error",
"log_output",
"log_queries_not_using_indexes",
"log_slave_updates",
"log_slow_admin_statements",
"log_slow_slave_statements",
"log_throttle_queries_not_using_indexes",
"log_warnings",
"long_query_time",
"low_priority_updates",
"lower_case_table_names",
"master-info-repository",
"master_verify_checksum",
"max_allowed_packet",
"max_binlog_cache_size",
"max_binlog_size",
"max_binlog_stmt_cache_size",
"max_connect_errors",
"max_connections",
"max_delayed_threads",
"max_error_count",
"max_heap_table_size",
"max_insert_delayed_threads",
"max_join_size",
"max_length_for_sort_data",
"max_prepared_stmt_count",
"max_seeks_for_key",
"max_sort_length",
"max_sp_recursion_depth",
"max_tmp_tables",
"max_user_connections",
"max_write_lock_count",
"metadata_locks_cache_size",
"min_examined_row_limit",
"myisam_data_pointer_size",
"myisam_max_sort_file_size",
"myisam_mmap_size",
"myisam_sort_buffer_size",
"myisam_stats_method",
"myisam_use_mmap",
"net_buffer_length",
"net_read_timeout",
"net_retry_count",
"net_write_timeout",
"old-style-user-limits",
"old_passwords",
"optimizer_prune_level",
"optimizer_search_depth",
"optimizer_switch",
"optimizer_trace",
"optimizer_trace_features",
"optimizer_trace_limit",
"optimizer_trace_max_mem_size",
"optimizer_trace_offset",
"performance_schema",
"performance_schema_accounts_size",
"performance_schema_digests_size",
"performance_schema_events_stages_history_long_size",
"performance_schema_events_stages_history_size",
"performance_schema_events_statements_history_long_size",
"performance_schema_events_statements_history_size",
"performance_schema_events_waits_history_long_size",
"performance_schema_events_waits_history_size",
"performance_schema_hosts_size",
"performance_schema_max_cond_classes",
"performance_schema_max_cond_instances",
"performance_schema_max_file_classes",
"performance_schema_max_file_handles",
"performance_schema_max_file_instances",
"performance_schema_max_mutex_classes",
"performance_schema_max_mutex_instances",
"performance_schema_max_rwlock_classes",
"performance_schema_max_rwlock_instances",
"performance_schema_max_socket_classes",
"performance_schema_max_socket_instances",
"performance_schema_max_stage_classes",
"performance_schema_max_statement_classes",
"performance_schema_max_table_handles",
"performance_schema_max_table_instances",
"performance_schema_max_thread_classes",
"performance_schema_max_thread_instances",
"performance_schema_session_connect_attrs_size",
"performance_schema_setup_actors_size",
"performance_schema_setup_objects_size",
"performance_schema_users_size",
"pid_file",
"plugin_dir",
"port",
"preload_buffer_size",
"profiling_history_size",
"query_alloc_block_size",
"query_cache_limit",
"query_cache_min_res_unit",
"query_cache_size",
"query_cache_type",
"query_cache_wlock_invalidate",
"query_prealloc_size",
"range_alloc_block_size",
"read_buffer_size",
"read_only",
"read_rnd_buffer_size",
"relay-log",
"relay_log_info_repository",
"relay_log_recovery",
"safe-user-create",
"secure_auth",
"secure_file_priv",
"server_id",
"simplified_binlog_gtid_recovery",
"skip-character-set-client-handshake",
"skip-slave-start",
"skip_external_locking",
"skip_name_resolve",
"skip_show_database",
"slave_checkpoint_group",
"slave_checkpoint_period",
"slave_parallel_workers",
"slave_pending_jobs_size_max",
"slave_sql_verify_checksum",
"slave_type_conversions",
"slow_launch_time",
"slow_query_log",
"slow_query_log_file",
"socket",
"sort_buffer_size",
"sql_mode",
"sql_select_limit",
"stored_program_cache",
"sync_binlog",
"sync_frm",
"sync_master_info",
"sync_relay_log",
"sync_relay_log_info",
"sysdate-is-now",
"table_definition_cache",
"table_open_cache",
"table_open_cache_instances",
"temp-pool",
"thread_cache_size",
"thread_stack",
"time_zone",
"timed_mutexes",
"tmp_table_size",
"tmpdir",
"transaction_alloc_block_size",
"transaction_prealloc_size",
"tx_isolation",
"updatable_views_with_limit",
"validate-password",
"validate_password_dictionary_file",
"validate_password_length",
"validate_password_mixed_case_count",
"validate_password_number_count",
"validate_password_policy",
"validate_password_special_char_count",
"wait_timeout"
]
