We have multiple mentionings of young women in liturgical roles, both from the scripture and from written tradition. It is not therefore an implausible one-off fantasy of "some Rabbi". It shows that the institute of temple virgins existed during the Second Temple period.
The quotes from the Mishna show no such thing no matter what mss. is being quoted and thus the above is reading more into it and the Scriptures referenced then is there.
In saying: “We have multiple mentionings of young women in liturgical roles, both from the scripture and from written tradition”... there is nothing that suggests temple virgins.
“liturgical roles”? What exactly are you talking about and does how that translate into “temple virgins”?
What you are left with is apocryphal writings and Marshall's assertions, if that. If that's sufficient for you, well and good for you. But please don't tell me that women serving outside the tabernacle equals temple virgins, it's like asking me to not see what I see or read.