So there's this script called Pseudo Effect Maker: https://aescripts.com/pseudo-effect-maker/

It lets you make your own pseudo effect without writing code in PseudoEffects.xml.

I want my script to have the same functionality but I have no idea how I should approach it. Any suggestions?

And make buttons move down to the next row if there isn't enough room?

I know I can set the orientation to row but that keeps all the buttons on the same row even if there isn't room for all of them.