Great to hear things seem to be better with the engine. I've yet to get my startup as the weather has been bad and other things got in the way. Also wasn't able to ask my buddy about it for you either.
Have you managed to setup everything on the G3X for the Rotax? If not, here's what I've done....

When you startup make sure you enter configuration mode on the G3X. Once up, I turn on my backup power and switch on lane one A and B so that the engine readings come alive. On the main system info page you should see under the device list FADEC 912iS_Sport with a green checkmark. It will be and X if you don't have lanes on. You should see all of the details listed on the right page. It's also a good spot to look at throttle reading to see what % it's reading as you move it in and out - that way you can verify that's working since you mentioned some concerns there.

Next head on over to the GEA24 setup page. Make sure cylinder head temp is disabled as it's not required. You should see FADEX for the next 4 items, then your fuel pressure and FADEC on RPM1. Scroll down to Pos6/GP 6 and configure it to coolent emp (fadec) and then Pos7/GP7 configured to manifold air temp (FADEC). I think those are the key items from the FADEX inputs.

I've put in for my final inspection as well - likely first thing in the new year. Lots of little things to clean up. A few small deficiencies I've found but nothing major.