Default email language
Right now as we know Booking.com guests are assigned unique Alias emails for communication/profiles. If a guest receives a confirmation email (despite the property being in German for example) the email is automatically sent in English as Mews will by default sent it in English to any profile that does not have a language associated to it.
This is despite the property being in a German environment.
Not only in confirmation e-mails. Also in invoices (I do not understand that once a guest has set his language, billing mews does not automatically suggest guest language in order to print or send). All communication with guest, should whenever possible and translation available, be in guest language
Claas Normann Mäder commented