When displaying an item or property page, the page heading applies language fallback to the label and description
e.g.
- On https://test.wikidata.org/wiki/Q38378?uselang=de-ch de-ch falls back to de for the label and en for the description
- On https://test.wikidata.org/wiki/Q38379?uselang=de-ch de-ch falls back to en for the label and de for the description
Doing anything with the termbox which causes the heading to update causes the language fallback to no longer be applied
e.g.
- Make any change and save it. After saving the heading is refreshed and no longer applies language fallback
- Make any change to the language currently set as the interface language, no save needed. The heading updates immediately, no longer applying language fallback
- Make any change to the language current set as the interface language and then cancel editing. The heading updates when making the changes, the changes are reverted after cancelling, but language fallback is no longer applied
I would expect the heading to always be consistent - what I see after saving/cancelling should match what I see if I then refresh the page.