This Avar-Tsez isogloss is rather interesting, because it is certainly an old Iranian (Scythian) loanword, ultimately going back to a Germanic source (Proto-Germanic *aluδ 'beer' < PIE *alut-). The root is still present in Osset. älūton, and was also borrowed (probably from an early Ossetian source) into Georg. ludi (dial. aludi) 'beer' - see Abayev 1,130-131. Regardless of whether this loanword penetrated East Caucasian languages during the period of the Avaro-Ando-Tsezian unity or somewhat later, it must have been borrowed before the change *l > r occurred in Avaro-Andian (unfortunately, Tsez. -r- here is uninformative: it can go back to both PTs *-r- and -l-).