Continue the story. (keep reading); Continue the trial. (suspend)
Drop the album. (release); Drop the charges. (abandon)
Sanction an event. (approve); Sanction a country. (penalize)
Cleave to principles. (stick); Cleave wood. (split)
Clip keys to belt. (attach); Clip the hedges. (cut off)
Dust shelves. (remove); Dust pastries with sugar. (add)
Hold fast. (fixed in place); Walk fast. (moving quickly)
Make oversight. (omission); Provide oversight. (scrutiny)
Peruse the ancient manuscript. (read in detail); Peruse the magazine. (look through casually)
The alarm went off. (activated); Turn the alarm off. (deactivated)
It's yet to be found. (not found); Yet it's found. (found)
They're all but forgotten. (nearly); They're known but to God. (only)
I guess I am just unable to parse the words to piece together such a meaning. In my mind, there are two ways to interpret it: "this subject may be all kinds of things, but one thing it is not" (all but = everything except), or the opposite "this subject may be all kinds of things, but one thing it is for sure". And neither of these means "nearly" :(
You've walked all but the last step of the journey.
It seems like plain speech could be used, but this profoundly-irrational jargon was selected instead.
A table (if there even is one present at all) seems like about the least important part of a group discussion of an idea.
In contrast to the UK meaning which seems to be to take the topic from a briefcase under the table and place it for discussion on the table in front of everyone.