I wouldn’t be so keen on C#, as I feel VB is a better language, currently, but there is no doubt that if you are just starting out you will have an easier time of it in C#, since so many example are written in C#. MonoGame itself is C#, and Core is pretty much C# at this point, though that should be changing, or may have just changed.
If you have an existing program in VB, then it would make sense to stick with it, but then, you probably wouldn’t be needing templates if you had an existing program.
In all cases, you do need to be able to read C#, even if you don’t want to write in it. The C-family syntaxes have come to dominate language design over the last decade, or two. It’s a bit stultifying, but it does have to be understood.