Anyway, most often people are referring that "some game is not supported", but actually they aren't verified all UE4 versions, or even didn't try the game in UModel at all.
For example, yesterday I've got a request from one of more or less experienced UModel users, that Space Hulk: Deathwing
is not working in UModel, regarding the settings. However, today another one user informed me that the game works well, if user will set engine version to 4.12. This is just an example. The initial question about that game was like here - am I planning to support this game or not. Of course I'm not planning that, this game is already fully supported