[Risolto] Website only shows 1 language even though 4 others are translated

Background of the issue:
I am trying to add the other 4 languages so that they show up in the menu too. The other translations exist, according to the Translation Management. Link to a page where the issue can be seen: link nascosto

Symptoms:
Website only shows 1 language even though 4 others are translated. I expected to see 5 Languages. Instead, I got just 1 Language.

Questions:
Why are the other 4 languages not showing up in the menu?
How can I ensure all translated languages appear on the website?