When 617 and 9 Squadron bombed the Tirpitz, they were at 10.5k altitude and not a scratch, because they had a massive fighter escort and were above the smaller calibre AAA range.
I'd ask, how is it possible your enemy CV can be in vis range of a town and no-one is alerted.
I'd say it is fairly balanced. If the CV is protected by fighters, it is very hard to bomb true and accurately.
The issue seems to be with the B26 rather than the heavies.
The only way to get a heavy past a massive escort, is to have a massive escort.
Also bear in mind, some CV gunners are like aimbots, you literally can not fly straight and level.
This seems a realistic aspect of the game, some ships have dangerous gunnery, some don't. In WW2 there was a massive difference between British and Italian naval gunnery, so much so that it was a factor in British planning.
Read CS Forester's "The Ship". Names have been changed, but this is basically an autobiographical account of a naval battle, with key references to quality of naval gunnery.
Take into consideration as well, the amount of CV hunts that are fruitless, the amount of time involved in finding them.
If CVs can't be killed by a decent heavy pilot, then they would be like nuclear weapons in the game.
Don't forget WW2 was all about the shift from battleships sinking ships, to aircraft sinking ships. It should be possible.
Lastly as well, IRC Pearl Harbour and Taranto were conducted from a distance of 150 miles, not 2 miles offshore.