Sums up of problems and SOLUTION(S) for me. Don't want to spam the thread (sorry for another big post from me), but it's for doing the point of the situation on my side, and share a solution I found which works for me (THANK YOU LUCK).
1) Version doesn't seem up to date (easily solved with updating)
2) When you want to disclose your first country and push the "disclose" button in single player mode -> World War : you have the left menu which have time to "begin" to appear (sometimes without units inside) and it always crash. Same thing in Hot-seat mode (and I guess in other games modes).
3) (First) Training Mission -> Movement and Combat -- The tutorial tells you to select your Heavy Bot. You select it (sometimes it crash here), and then, tutorial tells you where you must send it : when you want to move it and click where it must go (or even somewhere else for what I saw), it always crash.
4) Briefings on campaign mode : I can't access them at all. When I begin a campaign, the briefing screen appears (without text) and is "skipped" automatically to load the mission.
5) When I select the Career mode in Single player, I click on which side I want to choose and... it crash (always).
6) No voices in training levels (voices who explain things to do etc..)
Solution to ALL OF THIS (except #1 of course):
Copy/past your game installation folder (the folder "Massive Assault - Phantom Renaissance" located in "C:\GOG Games\") somewhere else than the place it was initially installed (I tried to past it on my desktop), and launch the game with "mapr.exe" inside this copied folder of the game. That's all (you can uninstall the GOG version now by the way if you want more space). No need to update or anything else with this solution (I don't understand this at all).
But you still can solve some of the issues with updating the game (solve issue #2) and using the fix provided by Lord_Kane (solve issue#3)(but remember copy/pasting the folder solve ALL issues #2,3,4,5,6).
7) I don't have cinematics when I launch the game : it goes directly to the loading screen, don't know if it's normal.
8) Texts in training mission 2 goes too fast
9) Bad training mission name ("sc_train_o7_00")
10) No useful text in training mission sc_train_o7_00
11) No voices in training mission sc_train_o7_00
And new problem after pasting your game folder somewhere else (issues #2,3,4,5 and 6 should be solved if you're like me) :
12) Voices in Russian : voices are in russian instead of english in training missions and in campaign briefings. (But it seems that small in-game voices are english).
<span class="bold">The V3Fix provided by Lord_Kane</span> contain files wich solve issues 8, 9, 10 & 12.
Glory to him.
Issue #7 and #11 aren't solved, but it's not a big deal.
There is still
some issues, but I didn't encountered them, so can't to help for them.
Hope this will help, either players or GOG staff.