I can't shed any light, but I can thicken the plot up a li'l:
Once upon a time there was an addon I used, which I absolutely
cannot find any more- ronaldcargorope. I'd swear that one of the .pbo files HAD to reside in the mission folder itself- however. This was a long time ago, I had an older version of OFP back then, AND I cannot remember if this was even the case. It doesn't sound right at all, I know. But if anyone knows anything about this, or if it stirs up some vague memories for someone, please tell.
To your question: I have a *reasonably* good theoretical understanding of C++ and reasonable practical experience with Java - to my eye, the .cpp (C Plus Plus?) files are somewhat confusing: the use of the word 'class' especially, I don't quite understand what it means here..... things like defining classes within classes (like class All{}; within CfgAmmo{}; etc), having a semicolon after the final brace after a class description....
Other stuff looks familiar: like the array notation: cloudletColor[]={1,1,1,0}; for example. But then again, there's no declaring of variables.
What I think is, the .cpp files are kind of like chunks of information that the game code uses. They aren't true C++, but once again like ofpscript the syntax has been defined inside the game code (that we can't access), and the game knows how to parse it into information that it can access. It's undoubtedly more subtle than that. But you can't go writing your own methods there (or maybe you can...
)
Well, that's my theory, you'll notice I don't try and justify it because 1.) I can't and 2.) that would require work ;D but I suggest you go onto the
BIS forums and ask them.