You just have to check his website. In the References section, you can see that TFMX was created in 1989 for the Amiga, but not for the ST. _Never_ for the ST.
He didn't even do the music for the ST version, it seems, since it is not mentioned there, and that is a list of all his works.
I think he did not port the TFMX editor anywhere. As he says also on his page, the tool was cancelled due to problems with a softco, and never updated again. TFMX's only direct evolution is MusyX, available for Nintendo machines.
I thought you knew all about Hülsbeck?