The driver stopped supporting the "displaytoggle" action in 2010 [910dc6], but xsetwacom still accepts it.
Untested patch attached (I haven't even tried compiling it).
Commit: [910dc6]
Patch forwarded to the mailinglist for consideration.
Fixed in 0.25.0
Patch forwarded to the mailinglist for consideration.
Fixed in 0.25.0