I went over the Ennis holdings in the Charles Parker archive some years ago, mostly looking for recordings of Ennis' own playing. My recollection is hazy but there may have been radio programmes there as well.

RTE archives are here: https://www.rte.ie/archives/about/ with a contact

Someone like Peter Browne will have looked into that sort of thing but he is retired from RTE now.

You can try ITMA as well.