An important thing that it took me a long time to realize is it doesn't search file names by default, only file contents. To search by name you have to use the 'name:' prefix. This is nonsense, but it's also easy to overcome once you know about it.
It seems the worst offender of "type in exactly what the link / window header is titled, does not show up in results."
I haven't figured out if this stuff just isn't indexed, is de-ranked below everything else (my guess), or is using some weird non-user-visible tags that aren't named identically.