I've already implemented this change:
1 on forest
1 on jungle
1 on camps and plantations
2 on Ceilidh hall
Gives the total non-faith yield spread and weakens jungle compared to the current version. Buffs camps.
The overlap with Longhouse is a bit unfortunate, but oh well.
I think bonuses to unimproved stuff is a weird incentive to put on early pantheons. Check out my More Beliefs mod that is going to add an Enhancer that boosts unimproved features.wouldn't there be a balanced way to keep a yield on un-improved forests? It is a nice nod to vanilla, it feels quite immersive and unique, and offers an interesting trade-off. People find it too strong now, but the yields on un-improved forest are not currently disappearing on improvement. Maybe if it does it would be enough?
Epona has a long term issue that it doesn't give -25% BG Cost like Expanse does, so stacking modifiers with it is much harder. Tradition's super cheap tiles mitigate this to an extent, you might even want to just do a pit stop for Sovereignty while using it.