I was going to write that Love2D had an unusual drawback if you wanted to teach it to a 9-year-old: lots of third-party libraries had sexualized names.

However, this is outdated, and none of the recommended libraries can raise unwelcome questions with their names: https://love2d.org/wiki/Category:Libraries

On that page I see entries such as:

  - Grease
  - HUMP
  - Lovetoys
  - Löve Bone
  - Gspöt
  - Möan
  - fLUIds

To be fair, I doubt most children will question the names! And this is a small enough subset of the libraries that one can just avoid them.