We often receive questions from Belgian and Swiss properties to change the language of the "Your account has been created" email.

In countries, where there are multiple official languages (Belgium and Switzerland) the email is being sent in English. 

When the guest then clicks on Complete Registration button and logs into the Navigator (online check-in), he/she can change Nationality (Language) and from that time this language is recorded on the profile, and will always be used as the primary language for that guest.