Happy 18th!
The reason you can’t get food dyes in those colors that don’t taste terrible is probably because of what they are made of, it’s kinda hard to make new dyes that don’t photobleach – the same thing that your jeans do over time, sort of fade. The blue fades. Also on top of that they have to make them edible too. It’s apparently miserable (from someone I know who develops new dyes).