Any time you are going to try new coloring or finishing products you should try them out on scrap first. Different brands of dyes and paints might work differently. They might also work differently on different pieces of leather, so the scrap you try them on should be from the same hide of leather your project is from if possible. I haven't tried the eco flow cova colors so I don't know how they work but I wouldn't expect them to act as a resist for dye (but it could be interesting if they do). If I was going to use dye and paint on the same project, I think I'd dye it first, then do the painting over it. There is a chance that if you use paint over oil dye, the paint may not adhere to the leather really well. I think if I was going to do this, I'd dye up next to the dice with a brush. Then dye the rest of the belt with a dauber or however you usually do it (unless you dip the whole thing in dye). Then I'd paint the dice with the acrylic paint. Then I'd apply a sealer to the whole thing. If you want to add antique on top of that, you can. Then seal it again. Use up your scraps and see what works and what doesn't. Good luck!