This please. Great looking game so far. I'll be interested in reading how this all happened post game.
Well, I can start with Austria since they are probably in the weakest position after the first full round.
Russia made a ballsy move taking Veinna, but Austria isn't in a position to punish it because they misplayed Serbia/Rumania by sending the troop from Serbia into Rumania. With the Russian tank in Galicia, the more effective offensive and probably best overall option would have been to have Serbia support the troop movement from Budapest into Rumania. If Russia did what it did Austria would have traded 2-for-1 and gotten another unit during the build phase. If Russia would have went for Rumania, Russia would still have taken it but Austria wouldn't have lost anything. They still would be +1 SC for unit build.
A slightly less desirable defensive option would have been to camp the tank in Serbia (it wasn't going to get bounced before build) and to send the tank in Budapest to Veinna and gamble that Russia was going for it instead of Budapest or Rumania. That would give you a 2/3 shot of getting an extra unit. Worst case in that scenario would be Russia going full-greed, getting lucky and taking both Rumania and Budapest. Even in that situation, Austria would be left in a better-but-still-bad position board-wise than they currently are.
As a note, Austria is the most difficult country to play effectively. These situations highlight why as they almost always have multiple countries bearing down on them in the early game.