Non-Sunday feasts in the Maronite calendar tend to be either very old or fairly new. This is a fairly minor feast on the Maronite calendar, all things considered, so one might think it new. On the other hand, the Latin calendar gets the feast from Byzantine calendars, and Byzantine calendars get the feast from Syrian calendars, so, as a Syrian liturgy, its place in the Maronite year could go back very far. I simply don't have the extensive resources for liturgical history that would be required to say.
Feast of the Nativity of the Blessed Virgin Mary
2 Corinthians 4:1-6; Luke 8:16-21
O Mother of Light, your birth proclaims joy,
for from you rose the true Sun of justice;
He freed the world from its age-old darkness,
bringing light to those who seek to love God.
From you, O Virgin, the light of Christ dawns;
from your flesh the Image of God is born;
through your purity God brought purity,
and from the light of your faith, His glory.
Even in death, the souls are rejoicing;
with the angels, we exalt her fair name.
All who sing in reverence for her Son
exalt her name to all generations.
O Christ, from Mary, the true East, You came,
scattering the darkness of the ages!
O Light of our exile, shine in our hearts;
may the Mother of the Light pray for us.