kusala and kuthou

In a previous post I highlighted Gustaaf Houtman's explanation of the "Pali Trap", a concept which he uses to explain the tendency of anthropologists and other scholars to translate Myanmarised Pali terms according to their canonical Pali definitions rather than according to colloquial Myanmar usage.  Quoted below is a good example of such a "terminological shift" of a Pali word adopted into Myanmar, taken from Melford Spiro's Buddhism and Society: A great tradition and its Burmese vicissitudes, p. 97.

"In nibbanic Buddhism, it will be recalled, there is a distinction between kusala, good action, and puñña, merit acquired by such action.  Throughout the Therevada world, however, one or the other of these semantically distinctive lexemes--puñña and kusala--has been dropped and its meaning assimilated to that of the remaining lexeme.  "Merit" and "good," distinctive concepts in nibbanic Buddhism, have been fused into a semantically undifferentiated concept which is rendered by one lexeme alone.  Thus, in Ceylon and Thailand, kusala has been dropped in favor of puñña (Sinhalese, pin; Thai, boon), while in Burma puñña has been dropped in favour of kusala (Burmese, ku.thou)."

This "terminological shift" has led to the common Myanmar phrase "ကုသိုလ်ရတယ်" (kuthou-ya-day), meaning to "get merit" (as a result of doing a meritorious act). By contrast, as I understand it, according to canonical usage, one would "do" a kusala act and "get" puñña.