Hey @Timacek,
I’d first answer your last concern:
Though it says Last tested on: December 11, 2021, the description is old and refers to “all elements” of the first Cornerstone version. “All elements” were later called Classic Elements.
With that said, if you wish to have a single template and translate contents separately, you should use all Classic Elements and use the WPML’s Translation Editor
Otherwise, the translation should be done manually (https://theme.co/docs/wpml#translation). This is because the content V2 or the non-Classic elements are not available in the WordPress editor so I believe it’s technically hard if not impossible to integrate them with WPML, unlike the Classic elements.
Please stay tuned for future updates maybe there will be a way to make V2 elements translatable.
Thanks.