Were non-Vulgate Scriptural readings ever used at the pre-Vatican II Mass?
I believe the answer to this question to be yes.
If we count the lawful liturgical variants of the Tridentine Mass such as the Dominican Rite and the Carmelite Rite and permission given to some Religious Orders, we able to see that the Holy See has given various indults for the Tridentine Mass to be celebrated in various languages.
The use of the Greek language Scriptures in itself predates Jerome’s translation of the bible into Latin. The first three or four centuries the Mass at Rome was in Greek not Latin.
I strongly doubt the Hebrew was a Vulgate translation of Scriptures within the following examples:
Although Latin prevails in the West as a unified liturgical language, in the face of certain circumstances the Roman church has made exceptions to provide a language in the Liturgy more familiar to the people. It is in the ninth century among the Slavic nations that we find a departure from liturgical Latin in divine worship. A privilege was first granted to Sts. Cyril and Methodius, by Pope Hadrian II in 869, and again by Pope John VIII in 880 to use the vernacular (Slavonic) in the Liturgy.
Another example of the flexibility of which the Roman rite is capable is the privilege granted for the use of Chinese as a liturgical language. History records in the fourteenth century that the first Franciscan missionary to China, John of Monte Corvino, used the vernacular in the Liturgy.26 Pope Paul V, in a brief of June 27, 1615, granted the same privilege to Jesuit missionaries. As recently as 1949, the privilege to use the Chinese literary language in the Liturgy was granted by the Holy Office.
Still further concessions have been granted:
a) During the fourteenth century the Roman Liturgy in its Dominican variant was translated into Greek for use by the Dominican missionaries in Greece.
b) Permission had been granted to celebrate the Dominican Liturgy in the Armenian classical language in Armenia.
c) At the end of the sixteenth century missionaries of India of the Latin rite were allowed to celebrate Mass in Syriac.
d) In the seventeenth century the Discalced Carmelites were granted permission to use Arabic in their mission foundation in Persia.
e) In the seventeenth century the Theatine Clerics were granted permission to use Georgian or Armenian in their mission foundation in Georgia.
f) In the nineteenth century the Franciscans in the Holy Land were granted permission to use Arabic.
g) In 1958, an indult was granted India to use Hindi.
h) Five Latin priests in the Holy Land were granted permission to use Hebrew.
i) In 1959, the Holy See renewed Germany's privilege to use the vernacular (German) in the Epistle and Gospel after they are recited in Latin. - Liturgical Languages
As noted in point ”i”, Rome renewed Germany’s privilege to use to the German vernacular at Mass, in essence doubling the Epistles and the Gospels. When the original indult first came into effect is unknown (to me) at the moment.
The following may be of interest here:
After the invention of the printing press, prior to Luther's Bible being published in German, there had been over 20 versions of the whole Bible translated into the various German dialects (High and Low) by Catholics. Similarly, there were several vernacular versions of the Bible published in other languages both before and after the Reformation. The Church did condemn certain vernacular translations because of what it felt were bad translations and anti-Catholic notes (vernacular means native to a region or country). - Did the Catholic Church forbid Bible reading?
What is more is that Missale Romanum of 1965, allowed the vernacular, but did not state it had to be the Vulgate translation. There was no need if it were Greek.
The official text of the Ordinary is from the Roman Missal with English translations approved by the National Conference of Bishops of the United States, published by authority of the Bishops' Commission on the Liturgical Apostolate.
NOTE: This was the official English version of the Order of Mass from the 1965 Roman Missal, published directly after the Second Vatican Council ended in 1965. This was the English Mass used from 1965 until 1969-70, when Paul VI promulgated the New Order of Mass (Novus Ordo Missae), and imposed it on the Latin Rite (the Novus Ordo is the current normative Mass of the Latin Rite). This interim Mass is much closer to the intended fruit of Vatican II's Sacrosanctum Concilum than the New Mass of 1970. It is essentially the Tridentine Latin Mass in English with minor modifications.
Many rubrical similarities exist between the 1965 Missal and the New Mass of 1970. Obviously, an option for use of the vernacular exists in the1965. Furthermore, as in the Novus Ordo, it is at the discretion of the celebrant to either face the East ("ad orientem") or the people ("versus ad populum"). An option for concelebration was also introduced in the 1965 (this was formerly restricted to Ordination Masses).The required Mass vestments were also simplified (e.g., optionality of the maniple).In 1967, the cope was supressed in the Asperges (rite of aspersion at High Mass). The chasuble was worn in its stead. The Canon was still required to be read in Latin until 1967, when it was permitted in the vernacular. - The Interim Missal