Hi augus,
Sorry you are having a bit of trouble.
He actually looks good !
I would suggest covering three sides of the enclosure ( brown parer bag or the like - temporarily )
This will help him feel more secure.

So how is this little guy able to grab his crickets?
Crickets can't swim ( and cannot climb glass)
You have deep water in there -----for a red eye.
A red eyed tree frog would prefer a dampened substrate and a soaking dish with water that is not above it's chin.
You could use dampened paper towel temporarily - de-chlorinated water of course...and a shallow soaking dish with the same.

and/or

Consider feeding him in a bowl. ie clear glass - 3" sides- (like a pyrex type bowl)
Set it close to the back of the tank ( on the blue substrate /gravel) ---------near where he can climb down and sit on the edge of the bowl.

Lynn