Nice wall of text, really very nice 
One little suggestion:
This sounds as the 30° would be an fixed angle, but that isn’t the case. It hardly depends on the cover in front of the soldier, i.e. trees provides the lowest angles, rocks have wider and solid walls have almost the largest angles to provide protection.
Also it reads as the protection is somewhat ON or OFF, what is also not the case. Instead it starts from almost 100% (in the above mentioned angles) and goes approximately linear down to 0% dependant to the angle the shooter has to your soldier. So there are steps in between with partially covered body parts where you have a fair chance to not get hit, again dependant on the angle of the shooter.
In addition to that:
If you wish you can also include the screenshots that I made for another thread to show the behaviour when a soldier is behind a ‘high cover’ rock (there are also some useful hints in the whole thread, but unfortunately also a lot of offending and arguing):
A sincere apology for my last thread - #68 by MadSkunky