I've been playing around with the Accessibility Inspector, and it seems that there are both Title and Value which get read out. I don't seem to be able to set the value, though, as it is being derived down in the NSTextFieldCell, and it trumps whatever I try to set at the NSTextField level.
Another issue is when the text field has an empty string. I would like to have something read out by VO, but setting the title doesn't work.
All of this is being done in -tableView:viewForTableColumn:row:, but perhaps there's a better place to do it?
Ideally, I'd like to support back to 10.9, but I'm willing to use later if necessary.