Everyone who studied piano, until the advent of the formal music schools, had not one but two teachers. That is why when you read the bios of all the great pianists of the 19th century, they list their piano teachers, and they also list the person under whom they studied theory and composition.
It was expected that if you performed, then you would also be playing your own compositions. Anton Rubinstein, Busoni, Friedberg, Earl Wild, and even Horszowski wrote and played their own music.
Those pianists who were trained in this fashion visualized and heard a piece of music completely differently from the pianists of today. Carl Friedberg could sit in a chair, look at piece of music and then go to the piano and play it from memory.
When Prokofiev premiered his 3rd Concerto in New York, he visited Friedberg's class at Juilliard two days later, where it was performed on two pianos. Prokofiev complimented Friedberg's playing of the second piano part from memory, and asked him how long it took him to learn it. Friedberg replied that was simply the way he had heard it played with orchestra two days earlier.
So, yes, the way 19th century pianists played can be traced directly back to the score because by the time they performed a piece they knew everything structurally there was to know about it. Accordingly, they could hear in their minds ear what the composer was trying to say.
Kenneth Hamilton's book, "After The Golden Age: Romantic Pianism and Modern Performance," comments extensively on how most of the concert pianists of this era all insisted that their students pay meticulous attention to the score, yet none of them played that way.
Neal Peres da Costa's book, "Off The Record: Performing Practices In Romantic Piano Playing," has a companion website containing dozens of recorded examples which are cross-referenced on practically every page of his book.
Both of these internationally recognized applied musicologists, who are also concert pianists, extensively lay out the nature and historical validity of these playing techniques.
Finally, enclosed are You Tube links of Peres da Costa in performance utilizing this method of playing. In addition there are three You Tube performances by Mieczyslaw Horszowski in recital.
His first teacher was a student of Karol Mikuli (Chopin) and his second was Theodore Leschetizky. He was the longest living concert pianist in history having died at the age of 100 in 1993.
Peres da Costa
Horszowski