Since devs are finally fixing the missing intelligence limitation when learning spells, i.e. in BG2:EE you cannot learn or cast 9th level spells unless you have at least 18 int, Neera, Aerie, Imoen, Jan and Nalia can't cast these any more. Since most HLAs occupy 9th level spells slots, you can't use them either. Since Neera, Imoen and Nalia have 17 int, you can raise them to 18 fairly easily with Golden Ioun Stone that can be acquired in Saradush. Aerie and Jan however, can't really reach 18 without some extra effort.
I think its good to fix obvious bugs, but personally I think fixing this one has a major negative impact on the NPC choices you have in the game. Edwin just becomes too good, as if he wasn't already...
EDIT: Above is incorrect. Only scribing spells is affected by the limitation. So you can temporarily increase your Intelligence with potions for example to scribe spells and then cast them just fine afterwards. Also HLAs aren't affected at all.