On the tag synonyms page, I can see potential synonyms listed, and I see "pending(0)" in the right column, but I don't know how to vote on a proposed synonym. Can someone please explain?
On the synonyms page, click on a tag in the left-hand (Master) column for a row labeled as pending. That will take you to the synonyms page for that particular synonym. Near the bottom of the page, there will be a section saying Suggested synonyms with arrows next to it that can be used to vote.
This interaction's rather unintuitive....it really ought to be possible to vote from the synonyms page itself.