Thank you for your thoughtful replies, Dominique and Mark.
You encourage me, Dominique, to use the Attribute Browser on a more habitual basis, and adopt the habit you describe of reviewing Tags more regularly. (I'd read James Fallows' very interesting post on how he uses that browser, and filed it away. Partly (mostly!) I need to do the cognitive work, which has to do with my habit and not with Tinderbox, of corralling my messy pile of keywords: and develop a truly controlled (tag) vocabulary (borrowed from Andrew Abbott's useful Digital Paper, which I think I learned about here.)
It's very helpful to see how you and others use Tinderbox, and how you work with and process various data. Merci.