Well, I tried to push a formula as text into another formula, but I couldn't figure out how to escape all the quotes I'd need. Something like this would work in Excel:

If(true,"IF(TRUE,"&"""&SKY IS BLUE"&"""&","&"""&"SKY IS NOT BLUE)"&""","NEVER MIND")

It works, of course, with single quotes. the formula in tester is

If(true,[testerr])

But this also shows that I think you're right - a formula won't evaluate the output of another formula as its input.