Wikis with the Translate extension enabled suffer this problem:
1. Contributor translates all translation units of page ABC to language XYZ.
2. Master (English) version changes one word in one paragraph (one unit translation).
3. After marking for translation, the whole paragraph is marked as outdated (good), and then the whole paragraph appears in English at the page in language XYZ (bad most of the times).
Currently there are only two options when updating translation units:
* Ignore the changes. Translations won't be notified about the change. Not good when you add/change meaning.
* Apply changes. This will mark translation units affected as outdated, removing them from the displayed text. Not good if you just made a little change, but the old version in language XYZ is still more useful than a disruptive paragraph updated in English.
Allow a third option: apply changes, keep translations. The banner will still say that the translation is outdated. It could be even possible to provide a special look to the outdated strings e.g. light pink background (which would perhaps invite the reader to complete the translation). The banner has the link to the original English version, if someone is really curious about the details.
This way the translation admins would have full control deciding how a change in the English text should affect all current translations, without stressing out the translators because now a page looks half broken because of one word changed.
We asked more information from the people with direct knowledge of the topic: 500 translators who had real-life experience of invalidated translations. We got about 50 responses and the outcome is quite clear. https://meta.wikimedia.org/wiki/Meta_talk:Babylon#Should_FuzzyBot_remove_all_potentially_outdated_translations.3F