Use case:

I am translating the Translate extension to Finnish. There is a message that says something something aggregate groups something. I don't remember what is the previously used translation for it. I can find this by using the translation search and selecting "translated from English" option. This should be better integrated with the editor. Pau suggested that we could show search results when word or words are selected.

This is similar to T52092: Implement glossary (terminology) support, but instead of manually curated glossary, we would take advantage of the translation search by making it easier to access (directly from the translation interface).