The default behaviour when opening the media finder is to search for the title of the page.
This works really well in English, but fails badly in pretty much every other language, because 99% of commons is in English. I know structured data in commons will address this somewhat, but I suspect it will be a very very long time before have good language descriptions in other languages for all these images.
Meanwhile we could very quickly suggest images for these pages if we pull up images from the commons category, if one is linked, else fall back on the text search.
one UI complication is how to denote to the user this difference in behaviour from a normal text search. Maybe a prefix like commons:category:Mastitis, for example.
Case study: I've been systematically adding images to other language pages about https://www.wikidata.org/wiki/Q835061 - and I've noticed that nothing ever comes up when I open the media finder, even though the wikidata item has an image on it and a commons category (which I've added). It would actually reduce a step for me doing this if I didn't have to retype the name in English to find the images. :)