No translated stories in English, partial translations in other languages

[chunshek]

Describe the bug
Translation stories are not shown in English.
Only some stories are translated into other user languages, while others are shown in original languages.

To Reproduce
Steps to reproduce the behavior:

1. Go to Settings > General > Content Language > Custom
2. Select "English" as "Main Language". Do not select any other "Languages I speak"
3. Country categories now show "There are no significant stories in this category today."
4. Now select a language other than "English" as "Main Language"
5. All categories (including core categories and country categories) now show stories translated into the "Main Language" -- though not all stories are translated, some aren't.

Expected behavior

1. Translated stories from country categories are shown even if "Main Language" is English.
2. All stories are translated, instead of partially.

Screenshots
"Main language" set to "English": "World" shows all stories; "Taiwan" shows 0 stories. (Not shown: "Italy" also shows 0 stories.)

"Main language" set to "Italian": "World" shows all stories, but some are still in English; "Taiwan" shows all stories, but some are still in Chinese.

Environment (please complete the following information):

• Browser: Waterfox (Firefox fork)