Answer 1

Regarding the UI, if you want an honest opinion, your main menu looks bad. Do not use all capital letter, on the internet this has the meaning of YELLING. You could use a more elegant or distinguished font, but this is a minor question of taste/style. Two of your four menu items are boring legal stuff (Eula and privacy policy), I would hide those behind a settings or about icon... and don't spell out "please read". People will not read them anyway, it's just annoying, but you do your best to make the information accessible, that is good.
I am only writing this based on the playstore screenshots because I cannot try it (app is not available in my country).

Answer 2

Steven Warner
Converting an Android app from Java to C# or Python is generally not a straightforward process. It would require a significant rewrite of the codebase. However, you could use Xamarin or .NET to develop an Android app using C# or Kivy to develop an Android app using Python.

Answer 3

Your app isn't available in my country so I'm unable to download and try it but from the showcase on playstore, the widgets are quite blocky, I mean the button and the top app bar... Everything else looks nice but the uppercase menu label.

Converting this to C# means you will rewrite the source code in c# (which is unnecessary).

Honestly to me, the app doesn't look like the one originally made in java too judging by the look, there is no material design, android roboto font etc in it.