[Baertram]

Hardcoded is always bad if you got the way to determine it dynamically. imo
So LibSets is scanning the setIds once every API change. This shouldn't be a problem.
It also tells the users that it is doing this and forces them to do a simple reloadui afterwards. Takes 1 minute at all where you are even able to do whatever you want beside.
You could add ALL setIds to a list and update it manually so players don't have to do a scan. But seroiously: Who is going to maintain and update this if you can have it automated? I don't see any benefit in a hardcoded list.

And about localization: The SavedVars store the localized set names once they got scanned. If you change the client language the scan with this language will be done again and added to your SavedVars.
Within LibZone I've added the localization to the library so everyone got a base localization. One could implement this for LibSets as well, but currently I have not planned to do so.

Edit:
Currently working on LibSets to distinguish overland, dungeon and monster sets