Your apology is accepted!
Now back to our regular programming, which we join already in progress...
It never made sense to me that (a) one could install Rosetta into Lion and get any results at all, let alone get an installer written in PPC code to run; or (b) if installing Rosetta into Lion worked for an installer written in PPC code, then why wouldn't an application written in PPC code work also?
And the answer is...
Anytime an operating system is updated, there is a chance that some of your software will no longer function 100% correctly, until the publisher releases an update of that software for the newly updated operating system. And that is what is going on here...
The Final Cut Pro installer is NOT written in PowerPC code! There is some minor instruction in the installer that makes a call to the operating system in Lion, that Lion is incorrectly interpreting as being PPC code and hence giving the Dialog Box that says that it cannot run a PowerPC program.
This minor instruction is attempting to execute the following instruction in Terminal:
$ sudo installer -package /Volumes/Final\ Cut\ Studio/Installer/FinalCutStudio.mpkg -target /
If you execute this instruction in Terminal sans Rosetta, the program will install perfectly!
Somehow, the "installation of Rosetta" into Lion, and perhaps Mountain Lion interferes just enough between the program and the operating system, to allow the program to make this call to Terminal and install the program. Since this instruction will work in Terminal without Rosetta installed, it obviously has nothing to do with PowerPC code or Rosetta.
So the best advice would appear to be to use this instruction in Terminal and wait while the installation program completes all of its tasks with the concluding statement:
installer: The install was successful.
This method avoids any pitfalls that may occur by installing Rosetta, which has no place in Lion or Mountain Lion and may be the cause of future problems!
Since I do not have Final Cut Pro, I cannot confirm this, but maybe I can borrow a copy somewhere soon...