The Missing Glyphs window that pops up with a right click on the notification bubble in the left pane allows you to do multiple selections from the resulting list. I’ve found you can also copy the selection you make, but it pastes as things like “<GSGlyphInfo 0x60002b359b80> N:sha-cy.loclSRB.italic, U:n/a, Sc:cyrillic, Cat:Letter, SubCat:(null) case:lower production: uni0448.loclSRB.italic, LTR sort: italic.loclSRB.cy080 Components:(null)>.” I would find it (occasionally) useful if we could get the right-click > “Copy Glyph Names” options that we get from right clicking glyphs in Font or Edit windows.