I created new language in Admin like explained in second point from your linked page. I don't have XML extension

I also had report that numerous tables were updated / inserted, and also checked that  Section/Block/Key are correct - See image.



And English language is ok while Slovenian and German are not (showing: "button_add_to_cart" label).

Also data in looks ok:
select * from abi7_language_definitions where language_key="button_add_to_cart";
select * from abi7_languages;

I created new language thru Localisation || Languages and I loaded missing language data from default English language.

I checked language definitions for new language and there is translation present in new language. (like  button_add_to_cart --> "Add to Cart")

But when I change shop language to new language "Add to cart" button is shown as "button_add_to_cart". Also other translations are shown with key and not actual translation like:
"decimal_point" instead of ","
"text_home" instead of "home"

Text like "Unit price" is shown correctly. I cleared all cache.

Any suggestions?

Thanks.