@levitanus You have this at the top of your script
Content.makeFrontInterface(600, 500);
Content.makeFrontInterface(633, 300);
Pick one :p
I don't have scripts/CB.json so I can't do much else to debug.
This works for me though
Content.makeFrontInterface(600, 500);
const var key_low = 0x6000ffff;
Engine.setKeyColour(60, key_low);