i think being able to have a general respec to change initial origin character features, outside of when selecting an origin character as your pc (and even then i would want the variations to be limited), after recruiting them in the game world kind of works against the whole concept of origin characters and could create some real gameplay problems imo. these characters are party members that larian has specifically focused resources and writing towards to be unique in the bg3 plot, so i think the ability to effectively reroll stats (huge impact) or choose different cleric domains (and ive seen ppl in other threads suggest class changes too) likely wont happen, and again i dont think it should. this is actually tough for me, bc i usually prefer game design that gives players more options/choice, but i feel like the origin characters were created the way they were intentionally by larian to fit into bg3, either as a supporting origin character or as a leading player origin character themselves with designated storylines.
now if there were some specific gameplay functions or plot elements that were in game that the origin character could interact with that would allow for subclass or domain changes, that could be really neat - others on the forums have theorized that while playing with/as SH there could be gameplay elements that allow you to change your cleric domain/god, and i suppose that you could implement a similar mechanic for wyll too around the warlock patron and replacing or reaffirming your pact/boon - but i think that a standalone reset function wouldnt be a good design choice. if we got too much customization while 'in world' i think it would really reduce the importance of recruitable companions, as you could roughly respec the ones you 'want' in whatever roles you needed, and wouldnt need to create a party of different characters with established strengths/weaknesses, which i think would take away some of the strategic planning that should occur when you decide which party members to bring with you and where your day of adventuring is going once you leave camp. in my opinion, the more #s and more variety among the recruitable companions is the way to go in this aspect to give the player more options in deciding if they want to take for example SH as a trickery cleric over say another divine caster larian may have us run into later in game. that being said, i think once you find and recruit a companion, origin or not, whenever they level you should be able to have them level in any class you want - given they meet the attribute requirements.
regarding SH current stats tho - i totally get what you mean, lol. i was having the hardest time figuring out how larian was calculating ac and then saw her dex, smh SH. i tend to role clerics myself (hoping larian includes the arcana domain) so i havent really looked into a loadout set to compensate, so for now i guess lets hope we can give her a magic item to up her dex as now id largely look to keep her in the back line which tactically im not a fan of for divine casters normally and her skill choices also suffer from that low dex score. i had a similar problem with wyll's dex and also being initially limited to light armor given how i was playing him - gave him the moderate armor/shield feat and bumped his dex1 - maybe not most optimal, but ive been having fun with a tankier more close combat oriented blade of the frontiers.
(i kinda wish we could choose a feat at first level too so we got some more gameplay variance)