Ran the following tests on beta cluster:

CASE #0: ✅ (from this ticket: https://phabricator.wikimedia.org/T310613)

1. set your user language to "es"
2. load object Z10097 (which has a spanish label)

RESULT: the iso code 'en' appears to the left of the word FUNCTION

CASE #1: ❌
There are two problems with this case.

1. It appears the title (ex: "FUNCTION") only renders in English, even though it seems to exist in the i18n files for other languages.
2. There is no fallback for "english." If a ZObject has ONLY labels in non-English languages, when a user is viewing in English, it shows up as without a label

As a result of the combo of (1) and (2) this use case is impossible to test right now.

CASE #2: ✅

1. set your user language to anything but english
2. load object Z10018 (which only has english labels)

RESULT: the iso code 'en' appears to the left of the word FUNCTION (i.e. it is applying to both the word FUNCTION and the title, in this case "Convert C to F")

CASE #3: ✅

1. set your user language to "wo"
2. load object Z10099 (this object has a "fr" label, which is the first fallback language for "wo")

RESULT: the iso code 'en' appears to the left of the word FUNCTION and the iso code 'fr' appears to the left of the title ("le pizza")

Checking case #1:

• Added a Spanish label to Z8: https://wikifunctions.beta.wmflabs.org/wiki/Z8?view=zobject-viewer
• Set my user preferences to user language "es"
• Checked the following cases:

type has no label in my language, title does

• Url: https://wikifunctions.beta.wmflabs.org/wiki/Z8
  
• Result:
  • ✅ Title prefix "Type" in English showing [en] language tag
  • ✅ Title "Función" in Spanish with no language tag

type has no label in my language, title doesn't

• Url: https://wikifunctions.beta.wmflabs.org/wiki/Z10018
  
• Result:
  • ✅ Title prefix "Función" in Spanish with no language tag
  • ✅ Title "Convert C to F" in English with [en] language tag

neither type nor title have label

• Url: https://wikifunctions.beta.wmflabs.org/wiki/Z41
  
• Result:
  • ✅ Whole title "Boolean: true" in English with [en] language tag

With all this we can consider Case #1 as DONE, hence closing this task.