I have the same problem in Spanish. My relatives don't speak English and don't understand the invitation. It appears that no matter the language used for invitations, allways it goes in English. MyHeritage don't still have a multiple language for this topic. I suggest to MyHeritage to make an easy adition in the program allowing users to write their own text on a simple window during the invitation process.
I have similar problem, but I am working in program in Czech, it is publishing in Czech and family website is in Czech. But part of family is in USA so they completely dont understand sites in Czech. Co how can I switch publishing site to different language?
Before you invite an American relative to become a member of your family site,
Switch the display language to English. You can do this by clicking on the little flag at the bottom of the page.
Now go to the Invite More Family page, and send out the invitation.
The invitee will receive the invitation email in English, and will see the site in English display when he logs in.
Another thing you can do is input names into FTB in two languages, and then have both transcripts published to the site. Note that you will need to translate all your tree (or most of it) for this feature to work.