The identifier length part is already handled in Hibernate via Dialect#getMaxAliasLength. With that being said, if you look at HHH-7078 the plan is to incorporate:

• specific identifier length constraints by type (schema name, catalog name, table name, etc)
• handling of specific identifier length constraints by type into PhyscialNamingStrategy.

That should address your "identifier length" concerns.

As for temp table support, please:

• open a new Improvement JIRA requesting temp table support with FirebirdDialect
• create a GitHub pull request implementing said temp table support into the existing FirebirdDialect (https://github.com/hibernate/hibernate-orm/wiki/Contributing-Code)
• link the PR to the JIRA

Creating the PR is not essential, but helps prioritize this within the roadmaps.