This is maybe a bit niche, but I would buff navy tradition and nerf army tradition. By late game it's pretty easy to get army tradition in the 75-100 range after a big war and roll a bunch of great generals, but if you play normally (i.e. not focus all your effort on it for the memes and protect trade with 200% of your force limit), you're basically consigned to 10-30 navy tradition forever. I even took Naval Ideas in my most recent game—yes, unironically—and with its +1 fire and shock pips I was still sometimes rolling one star admirals. Since naval combat is extremely biased to favor quality over quantity and naval engagement depends strongly on admiral maneuver skill, NT is even more important to winning battles at sea than AT is on land.
Level 2 CoTs should have a small effect on NT, and level 3s should have a bigger one—it currently takes 5 Level 3 CoTs just to decrease NT decay from 5% to 4%, and sources of flat annual increases are incredibly sparse—just Naval Ideas and the Admin-Maritime policy for +1 each, plus several NIs. I also don't love that NT from protecting trade is scaled to force limit, since it punishes you for growing unless you make active use of what can become a huge force limit. I'm not quite sure what a good alternative is; maybe switching it to scaling with your currently deployed navy size, but that doesn't seem perfect either. In any case, it would be less important if NT were possible to find in other places outside of being one of the predestined naval powers or taking two very niche idea groups.