Im not familiar with the products that you are using, it looks like you have 3 components for the clear. Is the basecoat ready to spray or do you need a reducer for that too? The black should give you good coverage but red and yellow over black will probably be poor hiding. Stick with more light coats because if you get heavy it will take forever to dry. Im not sure that you need to wait 3 weeks for the black to dry, check with your supplier.

When you paint your cabinet black paint a piece of scrap too so you can test your red and yellow, then you will have an idea what to expect.

I dont think it should be necessary to wait days to put a second coat of automotive base on. The stuff is designed to be put on with a minimum flash time between coat with sanding optional only if needed. When I do a 2 tone on a car with product I use (standox) its typically 2 or 3 coats of the first color with 5 or 10 minutes between coats. 20 minutes later I am masking for the second color and ready to spray. 2 to 3 more coats for coverage and im ready for clear. Sanding might be needed if you wait to long, called recoat time and should be listed on your product. The spray can products will have much slower dry times.

It looks great overall. You have a plan to fix it, keep your head up and it will look great when you're done. Once its back together you'll forget all about it (mostly).

Looks really good so far. I always use 800 grit. Be careful on the corners. Then a scotchbrite pad on any shiny spots that are left.

Scuff to recoat time varies from product to product. The clear I use says 12 hours. I like to do a little more than just scotchbrite because you remove both texture and trash. Of course if you sand and buff at the end those will be removed in that step. Most sanding I do is by da sander so it goes quicker than by hand.

Looks really good. So what is your plan? Clear it 1 more time? You planning to sand and buff?

Congratulations, that is a beautiful pinbot. Looks fantastic.