Animals breaking stuff: could be tuned so that they only break stuff on water to only remove the boat exploit without enabling others. Endless discovery exploit could be fixed by making the animal attack instead of flee should it be unable to pathfind away.
Coal bug: should be fixed since it dosn't make sense, behaviour similar to steel crucibles (out leading to reset) or halving the q (of everything in the oven/kiln/smelter) would be a solution.
Mirkwood: The curios should get balancing so that there isn't an endgame top-something anymore
Fishing: could be fun, maybe only with the big rod, and in case you fail the game you're pulled into the water?
Pollution: no issue since the to-be-cured effect dosn't exist.