I’d try tuning it with the 54/42 setting if that’s all that is available. Raise the front mech, run through all the derailleur adjustments and give it a test ride. Choose at which point the front shifts and by how many in the rear. I’m new to it as well. My bike was actually super hard to setup in the beginning for some reason but now it’s easy. It was like I couldn’t get the bike to do what the app was asking of it. Some kind of communication issue loading the new settings I guess?

I'm new to syncro 12s (and indeed any electronic shifting). One thing I found was that there are two mappings for the syncro shift S1 and S2. First time I was uploading it to S1 but the mech was using S2 that I'd left as default.

I've not figured that I want different maps when on road and when on trainer. I do a lot of erg work on the trainer and on mech then used to use the front mech to accelerate the shift between 'on' and 'off'. But, with syncro then I need to ease off the power for longer than it would take to do the shift on mechanical and in that time then the resistance overtakes it and I get caught in a confusion between trainer, zwift and my legs in knowing what they want to do.

I still wish that pressing both shift buttons would force a change of the FD.