When adding alternative symbols, it defaults to the left side of the scale bar. If you forgot to add a symbol at the zoomed in/right side, you'll have to shift all the symbols manually. You can save them to styles, but it still takes a while on complex layers. It would be nice if you could choose where to drop in a new alternative symbol or at least give an option for the right side.
It would also be nice if you could click a button to autogenerate alternative symbols for every zoom level.
