Dear maahey: I searched for "flatterer proneur" and go this:
#935. Flatterer. -- N. flatterer, adulator; eulogist, euphemist; optimist, encomiast, laudator[Lat], whitewasher.

toady, toadeater[obs3]; sycophant, courtier, Sir Pertinax MacSycophant; flaneur[Fr], proneur[Fr]; puffer, touter[obs3], claqueur[Fr]; clawback[obs3], earwig, doer of dirty work; parasite, hanger-on &c. (servility) 886.

yes-man, suckup, ass-kisser [vulgar], brown-noser [vulgar], teacher's pet.

Phr. pessimum genus inimicorum laudantes [Lat][Tacitus].

I haven't had much luck with etymology of French words,
I get beyond my depth quicly.