The brown part looks normal. The urate is quite yellow and if I am not wrong also quite brownish. Ideally it is white to light yellow.
From what I know, this could mean two things: Either he has retained poop for a longer time in which case it can occur that urate is more on the yellow side...
I don't think hearing them can cause stress, because Chameleons lack the outer ear and therefor only can 'hear' very low frequencies. I would say the main problem is mixing two different climatic zones together. Red eye tree frogs are from the wet tropics while veiled are from moist valleys...
Welcome to the forum. Both are great species to begin with. I would make a decision based on the location you live in. If your location has naturally a higher temperature gradient and humidity is low to medium, a veiled might be good for a start. If you live in more humid and warm areas...