For 4 frogs you are looking for the biggest exo terra ( 36x18x36) if you want to keep them happy! 12x12x18 is not big enough even for 1 juvenile-adult, it is a prison.
18x18x24 is ok for 1 male, and on a smaller size if you happen to have a female. They are jumpers and moving lots at night, small spaces will stress them out.
Love red eyes!