As per Robert Harvey's suggestion here, lets have a review queue for tag synonyms. It should be filtered so that users will only be shown what they can vote on. This should help all those languishing tag synonyms.
My thoughts: (with the goal to minimize development time in mind)
The suggested synonyms page is already a good start.
Personally, I think it's slightly better than a review queue in the sense that you can actually search and sort. Perhaps this functionality should even be extended a bit.
What needs to change:
Currently the suggested synonyms page displays all suggested synonyms with tags you've got sufficient score in, even those that you've already voted on.
Allow voting directly from that page. Something like this:
Possibly add a link on the review page (to increase visibility - other suggestions welcome).
Optionally link the review badges to go along with it (???).
But, as there probably aren't too many tag suggestions each of us can vote on, since we need a score of 5 in the tag, I think the suggestion to allow high-reputation users to be exempt from this requirement needs to go in combination with this.