The code on the Github is a work in progress - I'm still changing stuff related to the hand controller.
I think I've already found and fixed the first issue of the check of the pin needing to be inverted.
The second one was well spotted. The PCMSKn register should be initialised but for some reason when I was moving the code around I seem to have lost that line. I've corrected the code in my working copy so it will push to Github next time I commit. That actually explains why the hand controller mode is no longer working at all as per @Pierre's report in the version of the firmware in this thread.
Additionally the speed detection doesn't work as you have reported - there was another mistake around line 616 in AstroEQ.cpp where the speed detection check is backwards - so pushing the button results in low speed instead of high speed. This is something I am still changing as we speak - I'm adding a third speed option whilst also trying to make it possible to do standalone guiding.
I would suggest holding off on trying anything to do with the hand controller mode for the time being until I've finished my latest round of changes. I'm currently waiting on a new PCB to upgrade my mount (which is currently V4.0 hardware from years back) so that I can properly test out the standalone mode. That won't come for a couple of weeks. Just know that I am working on it