Since no single fact ever 'proves' a theory, supported is the correct term to use. It's not the 'proves' vs 'supported' that is the operative argument. It is the 'therefore'.
"I suppose it could be said that someone is committing the fallacy if they said that its impossible for evolution to be false - but I dont think Ive ever seen that."
Evolution is based on assumed naturalism plus the fallacy of affirming the consequent. Evolution (P) 'predicts' change, Change (Q) is observed; therefore Evolution is supported. This is and will always be a fallacy unless all alternative to P are proved to be impossible.
“Since no single fact ever ‘proves’ a theory, supported is the correct term to use.”
—Well, yes, “supported” is the correct term to use because, as you say, no single fact ever ‘proves’ a theory - to claim otherwise would be the fallacy of affirming the consequent. People committing the fallacy would be those using the incorrect term of “proven”.
The point of the fallacy of affirming the consequent is that no matter how many ‘q’s one finds that SUPPORT ‘p’, one can’t state with absolute logical certainty that ‘p’ is true.
If someone says that an elephant walked through my backyard, I would look for elephant tracks. If I find what appear to be elephant tracks, then the claim that an elephant walked through my backyard would indeed be ‘supported’. However, it would be going to far - and be the fallacy of affirming the consequent - to say that the claim that an elephant walked through my backyard is now a logical certainty, since there are other ideas that are at least possible (e.g a prank).
“Evolution is based on assumed naturalism plus the fallacy of affirming the consequent.”
—Evolution isn’t based on ‘naturalism’ any moreso than any other theory. MOST people who believe in evolution are not, in fact, ‘naturalists’. Most aren’t even atheists.