AbsintheRed
Deity
While 23 is definitely not op, 32 is a 50% food buff which is very strong (and works fine for Vanilla Civ BTS). Add the island on lake Ladoga it becomes a 412 tile which seems way out of line. What about adding a building that adds flat health, something like Fishing Village. It could only be built on lakes. Then, the food bonus for lakes could be deleted.
About the Red Sea: Could it be hardcoded that any cities bordering the Red Sea start with Harbors? That won't be too op, would give access to the Fishing Village (health instead of the seafood bonuses!) and avoid the ability to build ships there.
The main problem is that it's not easy to separate lakes and sea tiles for the purposes of buildings.
Neither as prereqs, nor in the bonuses.
But harbours and lighthouses don't give bonus commerce yields. It would be either 32 for a freshwater lake or 23 for a saltwater lake. Neither of those seem particularly OP to me, given how few lakes there are, and the fact you would need to have a city right next to the lake to gain the bonus. After all, most of the smaller lakes on the current map are close enough to the coast that you can engineer the bonus for at least part of them by putting a city on the coast with the lake in the BFC.
I'm not sure if we should allow any of those naval buildings on salt lakes.