Heyo.
First of all - yes we understand your concerns about T4 CV and are constantly looking into how to improve the situation for all, without breaking the game for some people.
The most obvious, but flawed solution is giving hard cap for CV's - while it may help in some cases, it would actually make MM worse overall, without getting to the root of the problem.
With current CV popularity, matchmaker would just keep those CV in the queue, and then would just match them into weird battles, for example with 2 CV per side, and 2 not-cv ships per side, with 4 ships in the team.
Trying to solve everything only with balance, aka "Nerfing CV's into the ground" would also be a bad way to deal with this situation, so even with reducing the efficiency of ships we are exercising caution - for example with recent Hosho nerf - we did it, and now we are observing how it affected the game. Further adjustments may be needed.
So we are looking deeper into the situation and are looking for a smart solution to this problem, from several angles.
Fem,