I tried your suggestion of creating a stockpile closer to the scriptorium with the bins turned off, but it didn't seem to work. Then I realized I hadn't built a trade storehouse, which is one of the new buildings I hadn't seen in the manual before -- thx for the tip, btw, it's clearly of central importance now. Anyway, once the storehouse finished building it automatically opened up a crate of library supplies and a crate of feathers, and -- e viola! -- the scriptorium was functional.
So that's working, but now I seem to be having problems with my fish farm instead. Do you know if fishing poles and nets are one use items only, or how to prevent them from being stockpiled in a finished goods stockpile?