Carriers are in a very bad spot Currently and they deserve some attenction since the offer a very unique and flexible playstyle. I believe the following changes will make them viable instead of a 13k block defenceless target

Historically Aircraft carriers used small armaments to fend off torpedo boats, the equivilant of a torpedo boat on Nations is a destroyer(since corvettes are rarelly used for anything else than transport) hence upgrading to 6x 9Inch guns would make sense. this way a carrier can have a chance to deal with the swarms of destroyers sent after it without overshadowing "light cruisers"

Piloting a carrier does not increase your render distance and given their big size it makes it Very difficult even for more experienced pilots to manouver. Also when a carrier is attacked the attacker can freely fire while out of the carrier pilot's render distance