Could someone kindly throw some light on the etymology of these four words
from the Puggala Paññatti, and Pugglavaggo of the Anguttaranikaaya, Book
of Fours:

Ugghatitaññuu,
vipañcitaññuu,
neyyo,
padaparamo

The translation of the Bodhipakkhiya Diipanii by Venerable Ledi Sayaadaw
says that the first two are those who gain realisation of Dhamma on
meeting the Buddha "in person." I don't see this sense at all in the
commentary. Venerable Saariputta and Venerable Moggallaana both gained
realisation just on hearing the Dhamma, without meeting the Buddha in
person. They were clearly both of the Ugghatitaññuu type.