The icons we originally made to represent generic 'content types' such as quotations, definitions, textbooks etc. This was meant to help readers who might not know what the sister projects are. However, it turns out that it's hard to make icons that clearly represent these concepts (like a book icon vs textbook icon vs definition icon, they're all book-ish in the end) and an icon alone without any other visual distinctions doesn't convey this meaning. So I think moving away from these generic icons and using the project icons is the right move here. Then at least then, like @Gryllida says, users will be able to distinguish the project names easier.

So I think moving away from these generic icons and using the project icons is the right move here.

+1

do you think something like this (below) would work better?

Yes, though you should consider using the favicons (in the mock I see the full Wikinews logo; the favicon only has the globe).

Change 347368 had a related patch set uploaded (by Jdrewniak):
[mediawiki/core@master] [WIP] Revised styling of sister-search sidebar.

https://gerrit.wikimedia.org/r/347368

Change 347368 merged by jenkins-bot:
[mediawiki/core@master] Revised styling of sister-search sidebar.

https://gerrit.wikimedia.org/r/347368

Thanks, it's looking much better now: