It is unlikely that the frog will get big enough to eat the other fish. The Goldfish may possibly eat the frog. ACFs do get large (3-5"), but can only eat what they can stuff into their mouths whole. They have no teeth or tongues. However, I would not consider them compatible with Goldfish. They prefer much warmer temperatures than Goldfish can tolerate (79-82 degrees). Plus, they are nearly blind, and the Goldfish may eat all of the frog's food before it can find it.
The frog will be much better off in a solitary tank. 10 gallons is a good size for it, they have to surface to breathe, so a deep tank is not recommended. Do have a hood, they can jump really well!
As an aside, the Common Pleco is not compatible with Goldfish, either. Just FYI.
Hope this helps!
Hobbyist for many years, and I have an ACF.