Just spitballing but here's how I think the FNF mod gang would be affected by the Corruption:
Tricky: Supposedly he's immune because of how insanely powerful he is. So it wouldn't even touch him since "CAN'T CORRUPT CLOWN" (unless it somehow infiltrated his improbability drive).
Garcello: Tbh he'd feel hopeless like "what's the point", singing way fewer notes in Nerves (and still dying afterwards). But his ghost gets corrupted in an effort to force it back into his body. Though he manages to resist and fades away (with a frown instead of a smile).
Hex: Pulls a Papyrus, believing Corrupt!BF is still his friend and trying to reach through to him. But the corruption manifests itself as a virus that infects him. Corrupt!BF's lack of note inputs (done on purpose) allows the virus to destroy Hex's security systems.
Zardy: At first offers Corrupt!BF a place in his maze bc of his scariness, but when he sees he's truly a threat to his precious crops--he gets serious. The corn and pumpkins around him all wither/rot away, making him nervous.
Whitty: Recognizes BF and feels guilty for not apologizing to him for Ballistics' events. But he tries getting him to remember who he was, though the corruption makes Whitty a lot weaker (yet still a difficult and angry opponent).
Starecrown: Like Tricky, he's immune. But he sees Corrupt!BF as an "impostor" and wants him to prove that he's the real BF. Afterwards, Stare creates his own corrupted form to be "equal" with his idol (he's not afraid or concerned at all, it's merely fascination).
Sarvente: Immediate disgust. She wants Corrupt!BF and Corrupt!GF out of her church instantly, though by Worship she realizes she's been "tainted" and Ruv comes to her aid. But throughout his song the corruption gets to him. Finally, Sarvente manages to drive out the two in her final song, undoing Ruv's corruption.
Ruv stares out at the old, dry, brittle corn maze. He fowns. When was the last time he visited this place? Wasn't it closer to Valentine's day? He was... hoping to have Zardy join them again for a holiday. When the place was lush and green. Full of corn. He walks through the maze properly- as to respect his friend's wishes. Not to tread onto the crops.
He stops next to a pile of ashes, taking off his hat to reveal his very dark, purple hair. "H- hey Zardy.... it's been a while. I.... I'm really sorry. If I had known that- that thing would have done this I would have..." He's shaking as he silently apologizes. Practically pleading forgivness.
A ghost of the now deceased Scarecrow watches from a distance. Frown growing. He would have walked up to him. Probably given him a hug and explained it wasn't his fault... but was it worth ruining what was left of Ruv's sanity? Zardy sighs, staring towards what was left of his maze- of the other inhabitants and everything.
Zardy casually picked a corn stalk and examined it. "I know Ruv and Sarvnete always said they struggled with food due to money.... I hope this will suffice... even if only for a week.-" A small crunch was heard. Zardy pauses his work and looks around.
"Another intruder? Do these kids just not understand it when I say 'Keep Out'?" He gives an annoyed huff. He'll deal with it after he finishes the task at hand.
He stands up after picking what he felt was a decent amount of corn. While he was about to turn there was a large splash on his back- he assumed it was water and was about to shout at whomever thought it was funny but-
Somehow he smelt it right before the match hit his back. It was lighter fluid. He absoultely screamed in agony trying to put himself out to no avail. He looks to see who did it. Hazel grins evily at him.