Just looking at these sightings again, and this plant is confusing me. It looks more like P wilkinsoniorum than canaliculatum/keltonii/aff keltonii. Labellum callus is raised and dominates the labellum, the labellum is constricted in the middle, and the labellum is quite long and flat. The labellum groove is quite shallow, unlike most canaliculatum and keltonii, although there is some variation. The flowers look much longer (less squat) than P sp aff keltonii (Long Plain) although I've not seen that one before. Would like to see in the flesh one day - perhaps for the moment best left as Prasophyllum sp.
Looking at the images of each species in your new guide I would agree they are a better match for P. wilkinsoniorum. Don't have anything else to add, so am happy to leave as sp.