First of all: thanks for this app!! It's really what I was looking for. And it works like a charm. ;)
If I can make a suggestion, the box in wp-login.php to enter the Authy token isn't really intuitive. It confuses a lot of users (who don't know about Authy or can't even enable it because it's not enabled for their role). They've emailed me to ask how to login (they didn't understand that they should just enter username/password and login, leaving the Authy box empty).
My 2 cents :)