Register WordPress Users – Translate Custom Fields

Hi, I’m configuring a e-learning website that works with Buddypress plugin.
For register there are two parts.
First part is “Account Details” (user, mail, and password). This fields are provided for wordpress system
Second part “Profile Details”. The profile details are custom fields created by myself in:
Wordpress<Users<Profile Fields

The website I’m configuring is in two languages, Spanish and Portuguese. Spanish as a main languages
When I visit spanish version all form is in Spanish.
When I visit portuguese version all form is in portuguese exept the “Profile Details”.
That’s reasonable, all other register features are provided by the system, so if the system is in two languages this fields are translated automatically.
But I created custom fields, and the system don’t have in the .po .mo files this new items. So, custom profile fields are not translated.
I tried to solve, using [:es][:pt] in custom fields name to filter languages. This kind of code works in all website, but doesn’t works for profile custom fields.

Any Idea in how to translate this items?
Thanks in advance, Ula.

Using WordPress 3.9.2
Budypress 2.02
Mq Translate 2.6.7