I gotta say, I have a high general opinion of the author's writing, but this whole bit seems very sloppy and poorly researched.
Ball, ball, ball, the characters say.
Even surface-level research into the history of European group activities is enough to understand that ball is an extremely general term and that people seriously considering that activity would very seldom (if every) refer to it as simply a ball.
Because by itself, the term could refer to an extremely wide variety of events, many of which varied significantly depending on region and time period (some have even survived into modernity.)
Like, seriously, what do they mean, ball?
Do they mean football? Basketball? Or maybe even dodgeball?
I sure hope its the former because the latter two seem extremely anachronistic for the time and region that Tierra seems inspired by! But I wouldn't know, because it's all just ball to the author I guess.
Frankly - I am very disappointed. Do better. And, like, how about expanding your knowledge, man? Not everything in life is about sports.