Hi there, and thanks for the detailed feedback!
Some things are already known, you can always check that here:
https://forums.x-pilot.com/forums/topic/27194-ixeg-v15-for-x-plane-12-confirmed-bugs/
The Nav1 frequency will be "weird" in other X-Plane aircraft, too - I agree that it looks strange, but in subsequent use it will default to the previous frequency you had tuned during shutdown, so it should be a very transient problem.
The transponder code 7000 is for VFR flights in Germany, it is just an arbitrary choice. 2000 would be military night flying, 1200 is for VFR in the US.
Fluctuating numbers are measured very often, the pilot needs them to be updated all the time.
The documentation was not updated yet.
The clock´s year can not be changed (yet), that is a very low priority but maybe can be changed in the future.
The PROG page is still WIP, much of it´s content is not calculated correctly.
The fuel flow at idle is indeed a bug that will be fixed for the next version.
The effect of engine-anti-ice on fuel flow is negligible, we have not modeled it (just like the effect of winglets).
The plane will always turn the shortest way, if you turn the heading bug past 180 degrees, it will reverse the direction.
No, we won´t make a clickspot for all lights, but I might get Tom to make the inboard landing lights "toggle click" instead of "grab and pull".
Cheers, Jan