There could be any number of reasons why an orange peel look would occur, but perhaps first coating with Regal could cause problems. Regal is really not the ideal cabinet paint....it's more for walls. Stick with the Satin Impervo.

I'm kinda afraid to put a 2nd coat on the cabinet with the Impervo. Do you think it will somewhat hide or improve the look if i sand lightly and add the 2nd coat? DH says it doesn't look that bad, but I can really notice it, and i think it's going to drive me crazy!

It depends on how severe the orange peel texture is. Sometimes another coat will hide it and other times you may need to sand and/or apply a light skimcoat over it in order to hide it.

Foam rollers are crater makers. Fine for getting paint up but you need to quickly follow with a high quality brush to tip off. Test your skills first on the inside of a closet door to get the hang of it. In the meantime, let your cabinet doors dry a few days to harden up, then lightly sand them to smooth out the orange peel. Try the WBSI again - do one door and be sure you get the desired result, then do the rest.