First of all, the meagre 'search' in 'Manage Bookmarks' does not tell you where a 'found' bookmark IS, which makes it next to useless. (If ONLY it would tell you that in the list you see when you click the URL.)
Over the years (on DESKTOP, I can only guess the horrors on tinyscreen) I've developed a system of folders with generic names that I use to sort BMs as I add them. My 3 top categories - the only ones visible in the 'Toolbar' are OFTEN (frequently visited sites grouped by folder), RESOURCES (folders at the top are most-visited) and LOCAL (most-visited on top). I also use the 'New bookmark order' extension, which adds new bookmarks to THE TOP of whatever folder I put them in (easy to open and drag-into folder topic).
Works, but it's hardly ideal, that's for sure. Don't think anyone at Moz has addressed this design in years.)
One dollar won't buy much of anything. Give me a magic ten instead.