Looking for some documentation on the various boss scripts

Is there documentation somewhere on what each script entails? Most are self explanatory, but is Grong a ‘casting patchwork’ type fight? How does it differ from single target?

Grong is a boss in the Battle for Dazzar’alor raid from BfA.
That guide and video should help you understand it, you can also look at the boss script in the Theorycraft Wiki.

You can also find all of the other boss scripts that the robot will let you sim against, you could also make your own if you wanted to. You don’t have to start from scratch, you can make a copy of an existing one and modify it.
Fair warning, the learning curve is steep.