I re-filed a ticket yesterday (since they indicate 24 hours for a response), then saw they'd noted in the thread that the 24 hours was only Monday-Friday (no surprise there) but also that they were behind due to all the tickets being submitted for blueprints.
I have no idea if my new ticket puts me at the back again or what. My earliest submission that I know went through (via the auto-replies) was March 7th. I haven't had a non-automated response yet. Given my March 10th refresh, I think I will hold off on trying to follow up until this Friday. Maybe they'll give a better estimate as to how far behind they are in their forums, too.
Edit: I received an email just under an hour ago stating that I have been sent the blueprints. I am at work so I cannot verify in-game, but it is a custom response in email. They did respond to my latest ticket (I changed the subject slightly with each version I submitted so I could track which ones worked), which was provided about 21 hours prior, but I don't know if my place in queue was impacted by my earlier tickets or not.
Edit #2: I did receive all the blueprints I requested. Actually, I received them twice. Back on March 5th I sent a submission using a different email account. I got the notice for sending in a ticket but not the auto-reply to my response to the message, so I switched over to my Gmail account (which got both notifications). I also had my non-Gmail request filled, so I ended up with everything twice.
But that request was about 6 days old, so they seem to be quite behind.