WPML: how can I translate Hustle default strings?

Hello,

I understood that I must create two popups if I wan two languages. No problem here.
But, I’m not able to translate the Hustle text. I mean, for example:

(*) Enter your email address
(*) Name
(*) Email field is required

etc…

I scanned your plug-in with WPML, it found 2500 strings, but not these strings.
Can you suggest me what to do?

Thank you!