I have all three regis traded via home on my main account and the door will not open. Is this b/c they are traded or something else? Note I haven't caught the regis on this account yet.
You traded them
So for the doors to open, you need to complete the other Regi temples. If you haven't, then you can't enter the Regieleki/Regidrago temple. You need them on party and the Regieleki/Regidrago temple is meant to be the last. For traded, it doesn't work. I know when you want to skip things, I'm like that, but you can't skip this part, sorry.
Hope I helped!