When I add a new language and fill out the details form (/admin/config/regional/language/edit/de e.g. German), I use the language domain. There I have to add the protocol. But this added protocol overwrite the "normal" switch betwene http and https.
This means when I add http://www.page.de and open the page with http://www.page.de all is OK. But if I open the page with https://www.page.de all links are changed to http and i lost my https (in links an for form targets).
I think the protocol should be removed OR the module should change the protocol to the active one.
The check only happens on the domain name, both the protocol and port are ignored.