When I saw all the tutorials for conversion from unity to godot I didn't knew what was happening. Just today I learned about this. I'm sorry for thousands of game developers that now have to face crumbling split paths all leading downhill. Most of them have to start their work from scratch again, some delete their own games, and others have been putting their soul and body to a game that they might as well have to abandon.
But hey, you made a comprehensive list of engines, and if people learned at least a little bit of code, it can be easier to get to into another engine ( I'm not saying it's easy, rather that they know how development works, code can be quite similar in the other engine, etc...).
So now, it will be hard for them (or you, the reader), but there is a curve where, once you pickup from where you left off, path stops going all downhill and starts to go up (or at least the normal way).
So people, share this post if you know someone who has to face this, or simply if you can.