As time goes on in the world, the bosses become extremely Trivial. I can 2 shot bosses while barely taking any damage. Bosses are no fun in the endgame. Can you add something like how RPGDifficulty adds increased mob health and damage the longer your world has been played (number of days). Also, I feel like the 7 or so block melee range of bosses is just ridiculous. Bosses hit through walls without Line of Sight. The early game is too difficult but the endgame isn't fun. So when are the bosses actually interesting? I feel like a proper difficulty curve would make this more enjoyable

The curve is actually through the type of boss, there are easier bosses e.g. the skeleton with the shield and harder ones like the archmage or witch boss. The easier bosses spawn on weaker loot chests the harder bosses on better loot chests, so the curve should be according to the loot you can obtain.

Depending on the modpack you probably want to change the globalDifficultyMultiplier in the config to better fit.

Hitting through blocks is not a normal attack but rather an aoe melee whirlwind attack only some of the bosses have which they can only use every couple seconds

added a bit more config, for hp and damage seperatedly, if you want more than that you should make a datapack adjusting the bosses