I have not touched the FTV for a number of years ( thanks to Archie), but recently I ran into a PVP using v5.
I seemed to recall that starting from v5, v5.1 one can convert the MER file back to APA, so that was a big improvement from v4 and prior.
But then Rockwell introduced V6 and 64bit, and since then it's been either nightmare or a lot of hassle trying to find a 32 bit machine with FTV and then try to convert/export to the 64 bit.
To my surprise, v10 now can convert 32bit apa or 32bit mer file without the need of a 32 bit machine. The download size is huge over 2.5GB, but the software seemed to run much faster than my recollection.
However, the v5/v5.1/v6 mer file that it produce will not be able to convert back to apa file.