Several months later, and I've finally got a second opinion from a different vet.
This is a photo of his left eye as of October 31 for reference:
To summarize his thoughts; he believes this to be a congenital, cosmetic issue, or a benign cyst of sorts (paraphrasing.) There are no outward signs that point to infection and, with past flushings, no infectious materials came out. His heart sounds healthy, his bone density is good, no concerning curvature or kinks, and a strong grip. He said Spooble seems like a happy, healthy chameleon.
He said that, yeah, surgical intervention may fix this, but he, at this point, doesn't think the risk seems, as it's not interfering with his life in any way. If the bump stays around this size, constant flushings don't seem necessary either, as it's not obstructing his vision to the point of inhibiting function. I also shared a photo of that swelling from the last flushing, that took over a month to go away. The vet finds it best to leave it alone and not cause unnecessary discomfort.
He also noted that, if it was deficiencies in a vitamin, he expects to see both sides affected. Same with sinus infections.
Because it's only one eye that is affected, he really leans toward the cosmetic issue stance, especially since it's been like this since Spooble was a baby.
All in all, he seemed very honest and had even seen this sort of thing with chameleons prior. I sought out an appointment with him in particular because all the AK reptile groups always name him. I don't feel disappointed in the visit at all, even if I wasn't sent home with a treatment plan/medication of sorts that would "fix" this.
I will, of course, be diligent in observing Spooble's eye, as I have always been for the past 7, going on 8 months coming next week. I just thought, maybe, it'd be good information for the forum that perhaps sometimes there are birth defects that appear problematic, but are not due to an underlying health problem or infection.
Of course, I've gone to the vets like 6(?) times to reach this sort of conclusion, so it's best to get oddities like this checked out to rule out anything harmful.
Never assume something isn't an issue until it's been thoroughly checked, and even if this conclusion is reached, never become indifferent and continue to monitor for any major changes!
BONUS:
Spooble getting his heart listened to. He was so funny and squirmy.