due to the way they focus/shoot their tongue (from my understanding) it seems they would have an extremely difficult, if not impossible time to target/aim if they were to lose one of their eyes...
The people who have one eyed chameleons in that thread seem to say that there chameleons do ok, thankfully. Reptiles are a pretty resilient group of animals.
I have seen one eyed chams function pretty darn well like nothing is different in their daily routine. I'm sure just like a human or any other species at first it would be difficult to get used to. If you are thinking about depth perception (aiming) think about people with only one eye driving a car? Weird comparison yes.. but I bet you've never though about it. They get used to it and make due.
I have a panther who is over 7 years, one of his eyes doesn't seem to function much, but Arnold never misses a meal. He even complaints that I miss feeding him meals. He thinks he is human and wants to eat 3 times a day.
I found a post that has a couple of links that pertain to the way chameleons gauge distance https://www.chameleonforums.com/interesting-sites-60259/. Basically, the main way they gauge distance to an object is by how their eyes have to adjust to bring the object into focus, so they have the ability to gauge distance with each eye independently. This makes it so if they lose the function of one eye, they can still accurately gauge the distance of prey items with the remaining eye alone.