Liturgical research was conducted in large part by the Benedictines, although there were definitely others. And numerous bishops brought with them liturgical experts to Rome as the liturgy was one of the areas the Council was going to consider. Noted in reports of Vatican 2 was not only that fact, but also that the liturgical movement had been active for several decades prior to the Council.
You could substitute the word “scholarship” for the word "research if you wish; the point is, the issue of changes to the liturgy did not arise at the Council. There not only had been scholarly research done over the decades, but the result were also shared in Meetings, such as the Pastoral Liturgical Conference held in Assisi in 1956.
As an aside, much has been made about the move to the vernacular. What we tend to forget is that Latin is a western Europe language; but the Roman rite is not a western European rite; it is spread throughout the world. Interestingly, several of the strong proponents were from areas other than the West.
Bishop Willem van Bekkum of Ruteng, Indonesia was a strong proponent, and in fact had given a paper at the above noted conference.
The African born Archbishop Bernardin Gantin, head of the Cotonou archdiocese in Dahomey (now part of Benin, Africa was also a strong proponent of the vernacular, and was aware of how strongly other African bishops felt on the matter.
Archbishop Eugene D’Souza of Nagpur, India spoke at a press conference on the importance of the vernacular to a wider spread of Catholicism in India; likewise Bishop Lawrence Nagae of Urawa, Japan.
And while his comments are too long to reproduce here, Maximos IV Saigh, the Melchite Patriarch of Antioch, gave a rather blunt but rousing address to the Council.