@Cuttlefish There was an Into the Renaissance scenario mod years ago that used BNW mechanics, but it has sadly discontinued due to the sheer number of bugs as well as depending on other mods that no longer exist. I currently do not have plans to make a BNW version of the scenario, but may attempt such a project in the future.

As for using the ideology tree for each religion, it could be possible to set up LUA script in order to force a Civ to swap ideology trees when their majority religion changes. However, influence calculations seem to be hardcoded, so it would not be possible to make the conversion gradual. If I were to make it now, I would settle on simply making ideology trees based on Civ starting regions.