It appears there's been less than 500 suggested edits this year. That's less than 2 edits a day.
If there are really so few edits, I'd say it wouldn't be unreasonable to include regularly reviewing suggested edits in moderator responsibilities.
That should fairly trivially solve the problem of edits taking excessively long to be approved, without adding much of a burden on moderators.
(I don't know if moderators single-handedly approve edits, like with closure ... aside from the auto-approve when improving it that anyone with edit privileges can do. I don't think it would be a problem either way, but it would make it easier if they can.)
* If around 3 regular users review a handful of posts on a daily basis, that should also solve the problem, but this would be something some users need to decide to do on their own.