Not every word is translated?

Hi!

Great plugin, just to say first.
I have an issue with translation, more concretly .po files. Not every word on my site is translated. I have lates WP version, and latest UM version. I tried several languages, and i always get same issue:

error messages are not translated completly > when you get error red cloud message if value in field is not entered (for example if Username, First Name, Last Name or Password is not entered) you get message by default message: “First Name is required”. If I use .po files, I get “is required” translated, but “First Name” not. Same is with Last name, Password and Username.

What is interesting, in my .po file string “First Name” (and Last Name, Password and Username) are translated, and displayed correctly above text field, but in this cloud messages not.

if you want to check what I am talking about see https://www.pollab.rs/registracija/