snanam is not a native telugu word. Its a sanskrit word and since most indian languages especially south indian languages have heavy roots in Sanskrit there are a lot of similar words between the languages.
BTW snaanam is one such word that is used in Telugu, Tamil and Malayalam all the same... and the ending is also with "am" in all three. North indian languages adapted it without the "am" ending... and there the brahmin's or priests usual just say "snaan"
akka is a tamil word. But it is used in other states too.
I do think the writers are confused between the south indian languages though. I remember Ishita saying "Prandh" but that is a clearly Malayalam word that is never used in any other language. Half the time I have no idea what comes out of Ishita's mother's mouth. The "tamil" sounding words given to her are totally mis-pronounced to the extent that she seems to be talking in gibberish.
Recently though after Raman's speech, Ishita's dialogue to Mihika was well pronounced by Divyanka. Ishu and Mihika might be getting the hand of the language... but Ishu's mother is too far off.