So I have been doing some experimentation with Logic Pro X and FCPX and ran into something rather odd. Here's the background...
Short film sent to Logic via X2Pro with roles (which worked very well I might add). Once in logic I had 2 tracks of dialogue that I had routed with a bus to Aux 1. Aux 1 had a compressor on it. When I exported out an FCPXML the compression on Aux 1 did not get applied. If I did an AIFF bounce out of Logic however it was there.
I then took the compressor off of the Aux and dropped it straight to the dialogue tracks, and shut off the bus sending them to Aux 1. In this case they exported fine in the FCPXML.
So it appears that effects applied to an aux channel do not get passed through when sending out an FPCXML.
Correct, FCPX has no bussing ability, thus, that process can not physically translate. If it can't physically be done in FCPX, you're probably not going to see it in an LPX to FCPXML translation.
I rarely export FCPXML out of Logic, always AIFF, because I do some complex bus operations to have one audio source control effects on other audio sources. Such as automatic ducking, pitch correction, retiming, etc.