FM8 has more waveforms than Montage (FMX) has. I also believe the relationship between operators is arbitrary (not a set list of predefined algorithms) - so some "algorithms" that FM8 can realize may not be available using FMX.

That isn't to say you couldn't convert them in a "best fit" fashion where some FM8 "patches" sound close enough because FM8 draws within the FM-X lines.

A quick search doesn't turn up anything and most pushback sites the limitations I cited above along with other details of why an export from FM8 has not been accomplished yet.

The Native Instruments FM8 has a different approach to Frequency Modulation that includes some things not available in the FM-X engine.. so there are parameters that just would not translate... in fact, you might fashion a sound in the NI implementation of FM that would have no equivalent in the FM-X engine. The FM-X engine is based on the original DX FM (and to a great degree so is the NI FM8... but the devil is always in the details).

It is not so much the different Waveforms used as sources (both can start with different Wave shapes for FM) as it is the other NI additions, the Noise Generator, the Distortion, their Filter and like any different brand synthesizers, things like Key scaling, LFOs, and Envelopes will be different and have different characteristics and therefore cause a different resulting sound... the similar things might be handled completely differently in the Yamaha. And those NI additions can lead to a difference, as any two brands of products doing similar synthesis types would be different. Embrace the difference!

So if you are a seasoned FM programmer, you likely will be able to create the same basic tone on each system... but you would need to really sit with both to appreciate the different approaches to sound designing with Frequency Modulation... and trying to emulate those "extras" that now surround it.