That is super impressive! Thanks for sharing details; I would love to read a blog post about the game's development if you ever publish one.
I Dont think we'll be publishing a blog, as i made it with two random fellows i met locally, but if you're interested you can just look at the code, the git repository is public:
https://github.com/itaisinger/GMTK23Bowling
Here we are looking at the BallSpawnerScript.cs, specifically the levelUp function. Level is a int variable that increases each time you call this function. I made the ball spawning be random using a bunch of variable as the range in which it can be random, speed range angle range etc. The switch statement is what ties it all together.
The game manager calls this function every 10 seconds, which makes it increase the variables, and tweaking these lines i can basically create "levels", also downtimes and such.