Sorry but what you suggest is not my typical workflow. Chameleon is almost two years old and i’m going this way since the first update of it. Ofcourse there’s a logic behind it. First; i’m developing my product in the latest version of engine. This way i’m being sure that the possible changes in the engine doesn’t effect my product. Secondly; if i choose to follow your suggestion then i need to do this for let’s say three other older versions too. People also using 4.14/4.13/4.12 right? Actually there’s no visible line to make this backward compability clear. Third; there are nodes only available in latest version of the engine. 4.15 was came with a lot of new math nodes which i’m using right now. And this happens almost everytime new engine version released.
So what you can do about it? I strongly recommend updating your product to latest stable version of the engine (insert backup motto here). If you really can’t then create a new project with 4.16, import Chameleon to it and then migrate it to your 4.15 project. I can’t guarantee that the second option would be stable solution though.