While ideally this task could be accomplished from the workboard view, it would also be great (and I imagine easier to implement) if workboards and workboard columns were parameters on the advanced search page, so that I could create a query to return all open cards in the 'done' column on, for instance, the Team-Practices workboard, and then use the batch task editor to mark them resolved.

+1 for being able to search (and group by) workboard column.

In T1284#807613, @Awjrichards wrote:

While ideally this task could be accomplished from the workboard view, it would also be great (and I imagine easier to implement) if workboards and workboard columns were parameters on the advanced search page

That doesn't look easier to implement, if you consider that column names are arbitrary, change from project to project, and in our install we can have... how many different options?

I think the feature to pursue here still is "batch edits" on workboards. There is a similar request here: Make bulk moves easier on Workboards.

Isn't this one done? Workboard columns have a little arrow dropdown in the header, and if you are in Triagers, one of the choices is "Batch edit tasks...".