ATC instructions have to do with AI traffic. I have never used AI traffic so i cant find bugs in there.
I have pushed a update to the PA28 in trunk.
If you want, you can download and try it in 2020.3. The systems should work.
As far as i know the lights in trunk are already updated to Compositor, so you should only fly at daylight.
Compositor lights doesnt work in 2020.3.
But if the systems (comm, nav, ap, ATIS) work as expected, we will backport it to 2020.3.
https://sourceforge.net/p/flightgear/fgaddon/HEAD/tree/trunk/Aircraft/PA28/