Wake-up calls are always added in English language

When adding a wake-up call from the web interface it is always defined with the English language. So the call you receive is in English.
If you have configured another language and the wake-up call will be added from the phone itself with *68, the language is defined correctly.

The problem is that the language was not sent in the post when creating the new wake-up call:

array (
    [command] => savecall
    [module] => hotelwakeup
    [destination] => 6017
    [time] => 12:00am
    [day] => 10/06/2020
)

Missing 'language'.