I did very little work in Flash, and that's a different language called ActionScript. While the syntax is very similar to JS, it contains some nasty traps. Wait, what do you mean by Flash-like apps? What does Python have to do with that?
Well, you know python would be better at making 3D games, but Java would be better at making 2D games.
Also, I noticed Adobe Animate uses ActionScript thanks for the heads up I will defiantly be staying away from scripting in that, besides their user interface isn't so bad that scripting is necessary like with GMS2, but I suppose GMS2's user interface is more of a tutorial than anything else.
I am just abbreviating JavaScript into Java, but since Game maker studio 2 uses JavaScript and it is good at making 2D games but not 3D games one could assume the Unity is good at making 3D games with python and is bad at making 2D games.
Maybe... I haven't used python before it just feels kinda feels that way, either way I am open to being wrong.