Most other developers just use the default system and call it a day. Hot Start will do it 100% custom to match the real world equipment.
Not sure what you "fell for" considering no where does it say the add-on includes a weather radar. ¯\_(ツ)_/¯
I don't think the devs claim any compatibility (or incompatibility) with either solution. And I doubt they'll be installing them (especially as it's dubiously-supported payware). Can you provide more technical details? Such as captures from DataRefEditor? No-one else has reported these problems in 4 years since release. Thanks.
This is due to a simulator bug in 12.3, there is no known workaround. We are all waiting patiently for a fix to be released by Laminar Research. Sorry for the inconvenience.
The aircraft must be in trim, and the button must be held down for a few moments.
If you're still having trouble, please provide a video, preferably in high resolution.
I believe as this is a minimum requirement it (quite reasonably) assumes a 100% vanilla simulator running with all resources available to it (and Low-Medium graphics settings), which you do not have.
Have you tried what I suggested?