Above is the notification message sent to a customer who signed up with the Facebook Login feature.
When she reads this she may wonder if she's at a trustworthy place or at some amateurish junk run by a half-illiterate.
"Login" (in English) means the process of logging in, and nothing else. What is called by "login" in the message is actually "username".
You don't log in an account. You log in TO an account.
Guys, your stuff is not free, you know.
So, please, make this notification customizable or any notification for that matter, so we, the license holders, have the opportunity to make it look presentable to our prospective customers.
If it's, for some reason, asking for too much and "out of scope", at least hire native speakers to write copies for you.