After you file

My concern here is that the Agent wrote in the envelope the address Austin TX 73301 instead TX 78701

Probably yours was easy to forward to the right place since in your envelope was TX 78701

I hope they have implemented a system to process the mail to the right place fast However is weird that my acceptance Agent wrote right away the post TX 73301 and your mail was delivered also in TX 73301 Maybe they are processing ITINs also in this place.