For as lightning cometh out of the east and appeareth even into the west: so shall also the coming of the Son of man be (Mt 24:27).

Is it contrary to liturgical law to celebrate the renewed postconciliar Mass "Ad Orientem (To the East)"?

It is not. For a good treatment of this topic, see the Adoremus article from September 12, 2022.

Although it is allowed in the renewed postconciliar Mass, at Our Lady of the Holy Rosary Church in Hahnville, we celebrate liturgically "Ad Orientem" or "To the East" predominantly at the Traditional Latin Masses only. Our church in Hahnville is built facing West, so we can use the word "liturgically" with "ad Orientem" to describe this situation when the priest doesn't face the direction of East but rather faces the Cross with the faithful for the majority of the Mass. This "orientation" (pun intended) might be described also then as "Ad Deum" or "Towards God". The priest faces the Cross with the faithful because the Holy Sacrifice of the Mass is the renewal of the Holy Sacrifice of Calvary. The individual priest is not the focus—the focus is on Christ the High Priest.

For a more theological and historical perspective, read Pope Benedict's chapter "The Altar and the Direction of Liturgical Prayer" from The Spirit of the Liturgy, which is also available in the Adoremus publication.