Custom keyboard shortcut creation limited

I’m learning about bash script by writing one to setup all (or most of) my Ubuntu 18.04 customization. One of these are my keyboard shortcuts.

I’m using this answer strategy to config the hotkeys. However I observed it is accepting just the first 8 custom shortcuts I setup. I mean, the hotkeys that I store between custom0 and custom7 slots had been saved, but all others ignored.

Do someone have a clue about what could been happening?