Sissyfied is the wrong term. the correct terminology for cis females is femme (transformed tomboys would be feminized, or they underwent feminization). If it's a very slutty transformation, then they are bimbos (bimbofication). If they have a 1950's housewife vibe, they are Stepford Wives (stepfordization). "sissy" is a term describing extremely feminine and submissive (mentally ill)
cis-males, and shouldn't be applied to feminized tomboys.