I found a semi-solution…
WPML seems to work, but not always, with User Meta Pro, so I did this way:
– in WPML > Theme and Plugins Localization etc (sorry but I have an Italian version, so I’m not so sure about the title of the section)
– I searched and found “User Meta Pro” and checked it
– at the bottom of the page I clicked on “Scan selected plugin to find the strings” (or something)
– I come back to “User Meta Pro” and clicked on “View all plugin texts” (or something similar)
– at the bottom of this page I chose “ENGLISH” as “Original language” and clicked on “Save options and scan strings again”
– then I could begin to translate my strings
Because I didn’t find every string in this page (for example the text for notifications, like “Please wait until an admin confirm your account”), I installed another free plugin, Codestyling Localization, and there I could find and translate what I needed.
This is a partial solution, but it worked quite well for me.
Hope this can help.