They are compatible, but that is overstocked. You do have good filtrations I would say.
A single pair or 2 angels alone would need the 30 gallon by itself, so I would recommend getting one.
Like stated above, the rainbow shark are very territorial against their own species, so soon you are only going to end up with one. They also need 55 Gallons or more.
I would recommend bringing up the schools of the barbs and danios to at least 6 (also will reduce nipping with the angel, just watch carefully)