According to the Coppermind article, spanreeds are incapable of communication between the Physical and Cognitive Realms. I would guess they'd work just fine communicating between two points both within Shadesmar, if that's what you mean, just like they can communicate between two points within the Physical Realm - they just don't allow transfer of information between different Realms.
Spanreed question?
in Stormlight Archive
Posted
According to the Coppermind article, spanreeds are incapable of communication between the Physical and Cognitive Realms. I would guess they'd work just fine communicating between two points both within Shadesmar, if that's what you mean, just like they can communicate between two points within the Physical Realm - they just don't allow transfer of information between different Realms.