GP parley doesn't proc ludens echo?

Intended. Don't expect any different from Ezreal, either.

yeah, parrrley procs on hit effects like shiv and lifesteal not on spell effects like ludens and liandry's

GP's Q, Ez's Q, and Nasus' Q are, for almost all intents and purposes, auto attacks that deal more damage than normal. They do not proc Rylai's, Liandry's, or Luden's passives.