I can't speak for all Firebird users but personally I rarely have a
reason to resort to coding on the API directly. There are so many
good abstraction layers available there is really very little reason
to get down and dirty with the API.

Really what you are talking about is building yet another another
abstraction layer. If it were me, I would simply find one of the
existing abstraction layers and use it rather than trying to
re-engineer the existing API.