If therapy as a system cannot give clear methodology, scientific validation, replicable outcomes, transparency about risks and outcomes.. then it should not be be considered healthcare, should not be subsidized by tax and insurance, and should not be referred to as "treatment". It should be called what it is -- social experimentation.

If the OP is going to subject her "child parts" to a paid consultant for the purpose of healing something as serious as childhood trauma, the therapist ought to be very clear about what she is doing. If she can't, stopping would seem to be one viable option.