Main reason to settle near lakes is that they provide fresh water and allow to construct Gardens, it's not exactly about their own yield. If you have Resource Compendium and Resource Buildings mods, then there's also Lake Fish bonus resource and a building to improve the yield further (to +3 Food and +1 Faith, I suppose adding your mod on top for +4 Food can make sense, though I'm not sure if it's balanced compared to Farms and other benefits a lake gives).

@Nesano They all work fine for me. Nice little tweak; I feel as though maybe Lake Victoria could do with a bump up to 8 food in line with this!

This mod doesn't seem to be working, so I'm not sure any of the other ones work either.

If you ever want lakes to be ridiculous, you could use this mod in addition to the one that makes lighthouses apply to lake tiles (it makes them give 1 hammer a piece, I think).