Text Colour Hex
Hex values don't work for text colour. The colour picker in the UI editor provides hex value slider but the JSON generated turns this into a number (RGB maybe?).
This is a glitch that will be terribly difficult to fix. The problem is that the JSON exporter uses the stringification method of JUCE and it has no way of knowing if it should represent the number as hex number so it just uses the decimal representation which is extremely counterintuitive for colours.
But to be honest, I don't think this is a serious problem. Just define the colors using the colour picker and don't bother how they are represented in the JSON, or do you have a scenario where this is important?
I'm copying the font colours from my design in inkscape, which are provided as hex. I've tried using a hex to decimal conversion but that hasn't produced the same result that the JSON gives. My solution is to use the hex sliders in the colour picker and then copy what the JSON provides into my script - no big deal :)