I think the minimum line width for most fiber lasers with a galvo is 0.001, I found that the cut settings UI limits it to that, but material generator UI doesn’t (it’s probably a bug). So when you use line widths smaller than 0.001 as you are doing then who knows what line widths are actually used.
Do material tests with line widths starting from 0.001, not 0.0001. Also a few days ago I posted some of my material tests for colors on steel, they include some nice red and other colors in a post here, you might find them useful, at least as a starting point.