The automation is volume + FX parameters -- reverb dry/wet mix balance changes for instance. Nothing unusual or particularly complex.
In some of the radio play scenes I am working on, there is dialogue between two characters which was recorded without good isolation, so I am manually "noise gating" with volume automation (one of the characters is on the phone so there is a radical tonal difference, thus any bleed is to be avoided). The automation is cutting very close to the dialogue so any drift is very audible. I am hearing LOTS OF DRIFT when doing a full-length bounce of the master mix, and also when trying to bounce all the short scenes individually, by selecting them all and trying to do a BIP for all. In the latter case Logic started at the beginning of the session and gave me back a single long WAV (not what I expected since I had rendered many individual scenes, which were their own unique regions, and unique regions should I think result in separate bounces). The timing of the automation was off starting around minute 12.
My latest strategy, which seems to be working, is to manually bounce each scene (they are each defined as a track stack, so I put an empty MIDI region on that lane to BIP it). Logic seems to be OK with short duration bounces and all the automation stays in place. Or maybe it is already starting to drift, but the amount is negligible.