Well with the 12 DDs the sovietski's suddenly have a fleet again. Have you considered 11 HS ES and full sized FG? Assuming the Sovietski's can build 11 HS/turn these two would be able to be pumped out. The FGs could mount 2P and a T this would make them very dangerous at close range to the warp point where they could tractor a ship and the next turn remove a critical system. The ES could carry F and snipe from long range (easily have -4 or -5 to hit). I did the first thing in my first game under like 2nd edition rules where I had 25 HS DD, 50 HS CA and 75 HS BCs that were "war" designs. I also used odd sized hulls in the munich game where I was playing a J engine race and had to like get them into jump carriers.
I think it is going to hinge a lot on what happens this turn...if the sovietski's get 3 turns to recover the warp point to sol will be seriously sewed up. If the D'bringi assault goes in before the RC alliance is formalised things will be more than a bit exciting.
The crabs are frankly at the point where they are starting to pose a serious threat to that colony. If nothing else the situation should drive home to the RC how untenable a shared system is when the peoples are not the best of friends.
The Tarek (crabs) really hate the Coalition, and humans in general, but, and this is a big but, they are firmly aware that the humans have at least one system beyond their own. And while the biggest ship they have seen is a cruiser, there is no guarantee that that is the biggest ship that the humans have. The Tarek really want to attack Wunderland, but fear human tech, which they know to be in advance of theirs, and the size of the human navy, which is a completely unknown data point. They have a goal, but are aware that they don't have enough information to have an intelligent plan to achieve that goal. Right now their plan is, essentially, (Growth+tech increase+something unknown but probably clever=victory). As long as there is that big unknown in the middle of the equation they will wait, and watch. For now. Unless they get even madder and just decide to throw everything out and go for the goal regardless.
In my previous campaigns I got irritated with the rules that said that a one-system, sometimes one planet, NPR would declare war on a galaxy-spanning empire, because "reasons". If they are crazy or chauvinistic that might happen, but it should be unusual for a race to declare war on a star-traveling race in that situation, in my opinion. That doesn't mean that they'll just bend over and take it, either, but open aggression against a race so powerful you aren't even a bump in the road to them is not a survival oriented decision.
Kurt