Agreed on yellow, I first thought it was paint. One nitpick though - you glued the katana the wrong end forward =)
I came to the same conclusion for orange but it's good to get your conformation (I'm still struggling with color rules). I made the mistake to start with a dark red while I should have start from pure white then a light red. Also, I tried to use the Vallejo fluo paints and they are quite not covering as I expected. I think the trick is to mix them with a bit of the same none fluo color to help cover. I did it at the last step by adding some white to the yellow fluo.
With fluo paints unless you have some intentional effect planned always start with pure white, otherwise they won't shine as well
Yeah, fluo paints don't cover worth a damn. Start with white base and then put the fluo on top of that, it's OK to be a little messy and get some fluo outside the white areas, that's just lightsplash.