I assume in these cases the pastor would have to have solid proof (eg. baptismal certificate) that the non-Catholic party was baptized with the Trinitarian formula.
My Protestant wife didn’t have a certificate, just the testimony of her mother, so my pastor included a request for a CONDITIONAL dispensation for disparity of cult when submitting my paperwork with the Diocese. (The Bishop’s permission was required anyway as he was also requesting a dispensation from canonical form for me). As far as I’m concerned my wife is baptized and our marriage is sacramental, but the Church errs on the side of caution.