It is very broad but clause A 2 eliminates spies, terrorist organizations, etc.
And terrorist organizations are ?
Not that simple.
Otherwise one side could declare everything and everyone on the other side a terrorist organization and do what they please. This sort of thing done between states at war will lead nowhere good. May I remind you where this broad reading of the convention came from - the Franco-Prussian war of 1870, where the invading Prussians often shot French partisans/francs-tireurs whenever they captured them. This was considered, at the time, an outrage. The Germans persisted in this interpretation in WWI, and even more so in WWII (note the Russian partisans fared even worse under this interpretation), after which the language we see was very deliberately adopted.
This is not new, well understood, standard international law for nearly 70 years now.
Therefore the law is broad and should be followed.
If someone is suspected of war crimes they should be prosecuted in a legitimate court.