... Thanks much Swagat ... indeed kewni केवणी or kewan केवण is more apt for H. isora. I have heard that from the local folks of Karnala say so.
Will try to dig into केव्नी kewni stated for M. calabura and be back sooner or later !!
(I also see now that the Marathi spelling केव्नी is inaccurate).
As far as Paanchara पांचारा for M. calabura in Marathi, the name is interesting (for one: ¿ is there any meaning to it ?) ... but just as Swagat says, it could be what the locals in a particular region call it. Else I could not find any mention on internet or reference books. Not-so-popular names is justified - the plant is non-native ... not sure how recently it got introduced.