Ogrovs and Starfish have light armour and so are countered by fighters which is bad.
They should have heavy or very heavy armour so that planet defenses hav a harder time destroying them.
Changing the armor from light to very heavy is not a good idea because bombers would to 100% damage vs them instead of 50% damage.
But changing the armor from light to heavy might just do the trick. Light Frigates would do 150% damage (instead of 75%) and fighters would do 50% damage (instead of 200%).
This would increase their survivability quite a bit!
The real problem with these things (particularly the starfish) is that they have to get in range of the starbase's abilities to attack it. The most obvious case is the starfish going up against an advent starbase, 2-3 meteors even a very large group of starfish will be wiped out. Given their excessive cost, it makes them pretty much pointless. You are much better off just massing a bunch of carriers with bombers for a strike force that no starbase can directly defend itself from.
The only real solution I can think of that would make them truly useful in their intended role is to give both the orgovs and the starfish supreme range, something like ~16, so they can bombard a starbase from well outside of it's defenses. Additionally something should be done to make them viable versus vasari starbases (which if fully upgraded will drive right over the top of them and just blow them all up). Perhaps some sort of fire on the move capability so they can continuously back away from an approaching vasari starbase would fix it. As it stands, against highly upgraded starbases these structure killers just don't cut it and massing bombers just seems like a better deal, particularly because the bombers are also very effective against enemy capships, heavy cruisers, etc.
I agree, the attack range of those cruisers is too limited. They need an "extreme range". Countering the Vas SB is always problematic, if the range of the anti-structure cruisers is increased, they would be able to take a few extra shots before the SB is on top on them.