forestcovered would be an excellent place for your characters! (And my compliments for playing them.) We fit the requirements - slow-to-medium pace, backtag friendly, our AC is 20 comments monthly and our app is fairly average, and no mandatory HMD.

Forest Covered, loosely based on Spirited Away, is a slice-of-life-with-plot-elements game where characters sign a contract to work on a resort island for spirits. In exchange they'll have a wish of theirs granted once they've paid off their debt. They lose their memory of their names, and are given work names to use instead, but they can regain their names later.