The worst part of this hobby is waiting for stuff to arrive in the mail. Mix ups are especially dis-heartening, especially when you're ready to rock out.
As for Topre stems, I've had only moderate success hand pouring my resins. I was hoping pressure would take care of the air bubbles but it seems like this is still an issue for you even with a pressure pot?
Also, interested to know what resin you were intending to use. I'm thinking of getting smooth on 310 for my translucent keycaps. I have some 326 that I'm waiting to use once I my setup is complete.