Either of those spots would be perfect. For me, though, those specific adventures would be once in a lifetime things that I wouldn't want to recreate just for a proposal (but if that fits their lives, go for it!). Instead, I'd consider sending them to a new special vacation destination with the goal to set up a romantic proposal for them, since they seem like an adventurous couple.
Or, I'd send them to Mt. Komorebi/Selvadora again but pick a more readily accessible, but equally scenic spot. One of my favorite proposals was during the Festival of Light. I had the couple make a wish together, then sent them onto the bridge where he proposed with the river all lit up behind them. If I were going to send them to Selvadora, I'd have them get a rental on the jungle side for a long romantic weekend. I'd do the proposal right at the beginning of the trailhead with all the ruins in the background.
I took a peek back at other old proposals, and it's hard to go wrong with bridges or waterfalls. Those are always very scenic spots.