Module presets should be stored elsewhere than in library.db
This has been mentioned only in a comment as far as I know, here:
My apologies if it has been opened before, but I didn't find anything.
But I would think that storing custom module presets and other custom settings would be better off in some other file than library.db.
The library database should be used only for actual picture data. While sorting and getting rid of duplicated images in my main photography folder and then rebuilding library.db from scratch, I noticed that presets were removed when I deleted the the library db.
This would make sense and stick closer to the KISS philosophy that we all love.