It looks like changing the order of items in getBuiltinQueryNames() in src/applications/search/query/PhabricatorSearchApplicationSearchEngine.php works for those accounts that still have the initial default order of searches and does not reset any custom orders set by existing account owners?

We aren't going to change the default in the upstream or prioritize document types within it -- it's not some weird mishmash like "commits and tasks", it's "all documents". I think this is the only reasonable default. Some installs do not use Maniphest at all, for example.

T4103 discusses allowing administrators to change default queries, home page applications, settings, dashboards, etc., for groups of users.

I think the patch @aklapper mentions should have the desired effect until then.

Even more confusing than mixed tasks and commits, I find mixed tasks and codereviews, since they will have the same title, and just use a different callsign. The texts "Commit" and "Revision" below the callsign do not help much, since many people use the terms interchangeably.

I'm going to merge this into T4103, although D12509 partially obsoletes it. Hopefully, the explicit control surfaced in D12509 resolves the confusion here on its own.