If you can't find help in the MariaDB documentation, you can also subscribe to the mailing lists or on Zulip to communicate with MariaDB users and developers.
There's an active help community on StackOverflow for programming with SQL and indexing questions, and DBA StackExchange for non-programming questions for example tuning/backups/architecture/migration/replication etc. Use the mariadb tag so questions are searchable by those that can help you.
You can report and check on bugs which apply to MariaDB in JIRA.