Under Linux, and I think Mac has a terminal console too, I have a copy of the whole library but I don’t have all the libraries loaded in the sym-lib-table.
:~$ grep -lir “LM317” .
(don’t forget the last dot) from the top directory of the library will find all the library files with the string LM317 inside.
I think another missing info is that once a symbol (or footprint) is placed you can open the symbol (or footprint) editor with this asset pre loaded from the right click context menu (edit in symbol or footprint editor is the entry and i think and there is even a hotkey which i however no longer remember)