Your letter was written by a drone, and most likely has an ink-stamped signature.
Again, ATF letters are non-binding. This means that they are not "get out of jail free" cards,even for the recipient.
Also, if you care to look, the form 1 is an "Application to manufacture".
Unless you're manufacturing in Siberia, or Brno, your new NFA weapon will be manufactured in the USA, and thus - not imported. 922r affects what? "Unimportable" weapons.
Apparently, this has not been discussed properly on this board, but it's been done to death on others (and I'm not quite ready to start copy/pasting all the content from those boards to this one).
OPINIONS DO NOT CHANGE THE LAW.