Dick, I recently had an American gent come to do some flying on a Certificate f Validation. CASA's ineptitude on this has been legendary since the advent of CLARC but regarding the English test, the FAA licence doesn't state a level of proficiency. As anything other than level 6 has an expiry it isn't acceptable elsewhere not to state a level. That is a burden the FAA have put on their licence holders that wish to fly overseas.
Easily sorted though, I was able to do his English test for a fraction of the rate you have stated ( though I have heard of places charging this not all of us do) and send the paperwork off to CASA.