I thought the exact same thing too but I've researched it and it actually improves heat rejection or dissipation vs when it was polished,It's coming along! How does painting the inter cooler black help keep it cool. Usually that's the opposite?
I did a very light coat to the core but the end tanks are painted completely.
My intercooler will be hidden in behind my bumper anyway so it won't see any sun.
I watched this video as part of research https://youtu.be/f1QL9veQaNg.
I'm hoping to have it running this weekend though.