I'm not sure if this is intended but I thought it might be an anomaly.
If you grab bag data like so
Code:
local bag = SHARED_INVENTORY:GenerateFullSlotData(nil,<some bags>)
and find a glyph and do IsItemLinkCrafted() on the data's "lnk" it will always fail.
But if you take the bag and slot ids from it and build a link like so: GetItemLink(bag.bagId,bag.slotIndex)
IsItemLinkCrafted() will return properly.