No, there is no easy way to determine what synths were used.
(Here's one possible method: name associations appear to be in library.db, which can be viewed with a hex editor. User-supplied plugin names are preceded by an MD5 hash that corresponds to the clsidPlugMD5 value in the registry, which in turn identifies the original name of the DLL. Like I said, no
easy way.)
Faced with your dilemma, I would substitute other instruments. As suggested above, it's quite likely the project would be improved. When I first got the OTS Rick bass I dropped it into an old throw-away project to test it out. It was such an enormous improvement that I ended up resurrecting the project, re-recording the bass part and remixing the whole thing. The end result was that a previously written-off project ended up being a finished song.
P.S. If we're talking traditional Hammond organ, grab
VB3. It's only 50 bucks and the best Hammond emulation I've ever heard.