1) "Mifrah" (مِفْرَح, with a kasra on م, a sukoon on ف, and a fatha on ر) means something that brings joy.
2) "Mifraah" (مِفْرَاح, with a kasra on م, a sukoon on ف, and a fatha on ر) means to be greatly joyful.
Based on these meanings, both names are permissible to use.
Allah the Almighty knows best.
Darul Ifta Al-Ikhlas, Karachi.
مصباح اللغات: (ص: 624، ط: دار الاشاعت)
فَرِحَ: خوش ہونا۔
المِفْراح: بہت زیادہ خوش۔