Happy Feast Day to you too!

Sadly, she is not mentioned on the SSPX calendar that I have. ( Already infected by the Nervous Disorder?)

No, it's just that Saint Philomena was never in the Universal Calendar of the Roman Church, but only in local diocesan Calendars or those proper to particular Religious Institutes. Therefore, the great Thaumaturge and glorious Virgin-Martyr is not found in most pre-1962 Calendars or Ordines.

From the tome Kyrie Eleison: Two Hundred Litanies with Historico-Liturgical Introduction and Notes by Rev. Fr. Benjamin Francis Musser, O.F.M. (Westminster, MD: The Newman Bookshop, 1944), here is a Litany in honor of St. Philomena, composed by another heavenly luminary, St. Jean-Baptise-Marie Vianney, the holy Curé d'Ars and celestial Patron of parochial Priests.