I think I was thinking that it would somehow twist their favored spells into an enemy-colored version of them? Or maybe force them into a mana inversion thing like Lucas Harran? I don't know, it's been a long week.

I'm past late about this, but I didn't have some epiphany so here we go. I'll suppose it turns every color into one enemy color, and magic will try to imitate its original use whenever possible.

Sharaka... would freak out. Like, a lot. Speed enhancement would turn into time acceleration, strenght enhancement... telekinesis? And that's alright. But fire would turn into snow magic and emotion magic would turn into
mind control. I think she would leave as soon as she accidentally controlled another creature, horrified out of her skin. Having Sophron-like powers is
not at the top of her to-do list.

Sharaka wouldn't mind too much. Sure, spitting light blasts would weird her out, but combat magic would be mostly unchanged. What would emotion magic become? Morale-boosting like
Djeru's Resolve? If so, she may find herself quite at home leading a team for some noble cause she deems fit. Connecting with a community is a big thing for her.
Elphimas' "active" magic is tied to the sentient spell living in their brain, so it would probably oppose some resistance to this magic warping, but I'm ignoring it for the sake of the answer.

Elphimas would find it an enlightening experience: sensing the life in the earth, the striving of every being from a blade of grass to a rampaging baloth... and when they discovered that shifting their own appearance resulted into full-fledged shapeshifting, they'd spend quite a lot of time on the plane, experimenting on how one's shape influences one's thoughts. There is the risk they would lose themselves in there, enraptured in a shape that doesn't feel loneliness or longing...

Elphimas would struggle a lot. Sensing emotions and heat instead of, well, shapes would be a serious difficulty for moving around. They might leave pretty quickly, feeling blind is not something they're fond of.
Snipe's magic
is artifice; as such, mana shift wouldn't have significant effects on their behavior. It would make using certain equipment impossible (if not using Moxes or other mana-shifting artifacts), sure, but once they got the hang of it there wouldn't be a problem. If they ended up shifting to

they'd probably return to build a small forge and produce Red-related artifacts to expand their arsenal.
Ungar has two colors, so he could change into


,


or


. They'd end up communing with the largest and most dangerous entity related to those colors (or riling up nations if

) and leading them to cause chaos, so it would be a change of tools rather than behavior.

would be a favorite of theirs, with all the possibilities to
destroy or
warp a plane, with

a close second with all its board resets (somebody said
Armageddon?)
Fayn is plane-bound, so there's that.
Shifted Kalit... if he manages to give the new mana color a chance, he might stop 'walking entirely. He would have been

if Thutmoset hadn't put his mark on him and dragged him toward psychopathy. Maybe

would be too stark of a contrast, and he would 'walk away quickly, but

calls to him. I'd like to think that this is what would take for him to settle down, find a way to reliably obtain his poison, and maybe find a community that is immune to it, or that can tolerate him while he researches an antidote to be able to be around someone without sickening them. Maybe a powerful druid would be able to reverse his curse? Possibilities abound.