While I generally like the idea of the "appeal" concept in Civ6 - and even its implementation to a large extend - I always scratch my head when it comes to terrain like Swamps, Floodplains and especially Rainforests. It just breaks immersion for me that removing Rainforest (except in the case of playing as Brazil) and Swamps is increasing appeal, beneficial or sometimes even needed to create a NP. Ideally by replacing it with secondary forest and putting a sawmill on top (which doesn't cost appeal), if only adjacent to the planned NP
It is the moment I always realize again that this fantastic idea sadly get overloaded by trying to tie in several effects (beauty, degree of "untouched nature", civil infrastructure like entertainment/culture as +, pollution, disease and disaster risk as -) in one factor (called apeal) which influences party very contrary features (National Parks, Tourism, capacity of Neighbourhoods). I see where the devs are coming from and the big advantage is that you have only a single value - but you pay for it with the oddities I mentioned. I would prefer a more compley model, where nature, civilization/entertainment level and diseases are handled separatly - influencing each other where it makes sense, but not by mixing everything up and calling it "appeal".