[...]From Falla I studied Canción, the score was difficult to find, the last part it's a bit tricky to play
https://www.youtube.com/watch?v=dElw1wRQ20E
Hi chechig,
that's a SUPER piece, I liked it very much!! Thank you for linking it!!
It may be in this volume, which I randomly..

found:
Manuel De Falla - Music For Piano Volume 2
ISBN 9780711961371
The second of two albums of piano music by Manuel De Falla. Includes: Cancion, Cortego De Gnomos, Vals-Capricho, Fantasia Baetica, and Canto De Los Remeros Del Vorga. Plus Dance Of The Miller's Wife and Dance Of The Corregidor (Danza Del Corregidor), from Three Cornered Hat.
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As far as preludes are concerned, I made up a short list of names who composed preludes of some kind. Of course I don't know how difficult they are, but perhaps one could find out via YT- recordings of these composers' preludes, whether one likes them or not? The list is in no way meant to be representative, I just came across some names while reading the Harenberg Klaviermusikführer. (Whose advantage compared to "wild searching through "preludes"-genre on IMSLP imho is, that there are some
selected "relevant, but not too well known, though, composers" mentioned in the book.)
Isaac Albeniz (who wrote another, but longer(!) work, in the title of which "prelude" appears: "Prelude Azulejo" op. post.:
https://www.youtube.com/watch?v=f0F4lkLlYvQ), Anatoli Alexandrow, C.V. Alkan, Anton Arenski, F. Busoni, G. Faure, C. Franck, Glasunow, Honegger, Kabalewski, Kirchner, Frank Martin, Bohuslav Martinu, Medtner, Messiaen, Moscheles, Poulenc, Reger, Rheinberger, Anton Rubinstein, Erik Satie, D. Schostakowitsch, Clara Schumann, K. Szymanowski, A. Tscherepnin.
Very cordially, 8_octaves.