In fact, Simcha id definitely a BOY’S name (and a “chidush” to use it for a girl’s name). We find nowhere in Tanach or Shas that any girl is called Simcha, but we DO find Simcha as a male name.
See Sukka 48b that there were two men heretics, one called Sosson and one called Simcha that were arguing whose name is “greater”,.. Simcha said the possuk says first his name: Layhudim hotsa ora v’simcha v’sosson…(see interesting debate).
The Machzor Vitri was written by Rabbeinu Simcha d’Vittara, a student of Rashi and grandfather of the SMAG.And Rabbeinu Simcha – the Baal Ha’Itur.
And one of the Baalei Tosfos was Rabbeinu Simcha, see tosfos Yuma 46b D”H Ki.
So I am on solid ground to state that SImcha is a male name, but where do you find support tostate that Simcha is a female name?!