I think a lot of this is going to depend on what you mean by 'bright'. I've run into this a lot with people when I'm getting something painted on commission.
Brightness means basically how much light they reflect. I'll say, what's strange is you aren't using white at all in that case.
The Charcoal is always going to struggle with that. As is the Blurple. If you have a sample set you can see that while it's a very saturated color, it doesn't 'glow' like it does on the design tool.
Do you maybe mean vivid instead of bright? This would capture brightness, intensity, colorful, contrast.
Not mine originally, but I've often found this to be a really vivid chip for example.
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