I think the problem with Esege is it carefully skirts around a pretty obvious rule for Epic ships. Rebels already had that advantage with Han crew though he was at least either or (still good though). The reason why Roark and Jonus/Howlrunner aren't issues is that everyone already has access to rerolls/PS boosting.
Apparently when created the epic ships were restricted in their ability to modify dice, particularly with focus. This seemed to be a balancing mechanic so that weren't too good, unfortunately it swung the other way and for most part they are fun, but not near as effective as the equivalent in ships. In hindsight the Epic ships actually needed the help. The conservative design approach has caused them issues that they have needed to be fixed by cards like Ordnance Tubes, Automated Protocols and whatever the other one is. While good cards I'm not sure Epic ships are quite there yet in terms of competitiveness.
The issue isn't so much that the Corvette can use the focus tokens, it's that the Imperials (and Scum) don't have access to that ability which skews the ships somewhat. I think one way to mitigate the issue is to not necessarily just reverse the ruling for Esege, but just give the Huge ships the ability to use energy in the stash to convert eyeballs to hits or evades. Sure this make them more powerful but at this point they probably need it. It also adds another element to tactics etc. It is a fairly simple line to add into the huge ships rules.