This is just a topic for me to post my test runs of fleet comps and situation using the dev exe. This is for my benefit as much as anyone else, so I'm just posting these in case anyone else is curious.
To test the "bombers OP" theory further I set up the following scenario:
An Advent gravity well containing 6 logistics structures, a starbase with 1 durability upgrade and no others, 2 PJIs, 2 repair plats, and a hangar (14 tactical); these are all grouped together so everything can benefit from shield bestowal and TK push can't be avoided; the mass of structures is closer to where the carriers will jump in than the advent ships
187 vespas sitting on the far end of the grav well, and a level 3 halcyon sitting next to the planet
40 percherons loaded up with bombers waiting to jump in
Upon jumping in I have the bombers dive the starbase. Switching players I frantically box-select 30 or so corvettes at a time and tell them to attack individual percherons instead of bombers. Meanwhile the halcyon lumbers over to the structures and moves in front of them. The starbase is at about 2000 hull when TK push goes off. I order the bombers to focus the halcyon instead; switching back I drag-select any corvettes I see attacking bombers and set them on the carriers, then spam TK push. I get 2 more pushes before the halcyon dies but when it goes down the bombers have been pretty decimated as the area they're flying around in is right next to the carriers and corvettes. I'm sure the corvettes overkilled some bombers to some extent, but combined with TK push and the grav well's 5 fighter wings they did enough that the remaining bombers (less than half the original) can't even overcome the starbase's repair + shield regen, so taking out any of the structures is a total non-prospect. From what I observed the corvettes will still fire some of their weapons at passing bombers even while focusing a carrier.
9 carriers were dead to corvette fire when I called it, far exceeding the cost of a halcyon in both resources and fleet supply. More importantly, the remaining 30 or so effectively can't retreat. First of all, PJI, and even after that they will lose all antimatter and more hull to the starbase. The nearly 200 corvettes are at 100% health and can chase the neutered carriers as long as they need to.
My only thought of a counter-strategy for the bomber player is to try and run his carriers past a "front line" world like this one and go to the inner ones which presumably have no defenses, but if the carriers have to cross grav wells instead of sitting on the edges, they're really putting themselves in a vulnerable spot to be decimated if the enemy fleet catches them.
These observations make me think that in a fleet battle mass bombers may be problematic, but manageable. Certainly it is not really possible to save the chosen target of the bomber swarm, but if a halcyon or kol is around along with a bunch of corvettes or flak the bombers will be pretty well done after nuking their one target, and I can't imagine that it wouldn't be a big handicap to have so much fleet supply rendered ineffective so quickly in exchange for just one capship. You might not even get one if it's Vasari with jam weapons. I guess the response from the bomber-spammer would be that his titan's AoE can deal with enemy flak or corvette spam, but I'm skeptical. Flak is very tanky, and while "optimal" micro would be impossible in a real game, splitting flaks into control groups of 15-20 would not be, and would protect the vast majority from AoE.
More tests coming. Eventually.