Thanks for flagging this before I shipped it — you called it exactly right. It's live now as a one-time prompt: the first time a player clears stage 5 (the first chapter boss), the results screen shows a short note suggesting they back up their save. Settings still has the manual export/import too, but it's no longer the only way to find it.
On the two smaller ones: agreed on both. "One button" is too specific a claim for drag-to-move, so I'm not going to check it — Touchscreen plus a line in the description covers it honestly. And you're right that 11 supported languages is buried; I'll get it into both the metadata and a line in the description text.
Thanks again — this is exactly the kind of note that's useful before shipping, not after.