You can't do this - animationsList&"_points" - with variable names.
You'll need a temporary variable s and a bunch of events like:
If CategoryNumber=1 Set s to Category1_points
If CategoryNumber=2 Set s to Category2_points
Or you can store your lists of points in a dictionary, under keys "Category1_points", "Category2_points" and do this:
s=PointsDictionary.Get("Category" & CategoryNumber & "_points")
Add int(tokenat(s, Sprite1.animationFrame, ",")) to totalPoints