Since I consider Robert Hughes to be one of this country's finest art critics, I always read his articles with great interest. However, I was surprised that in his sensitive review of ''Gothic and Renaissance Art in Nuremberg, 1300-1550'' (ART, May 26), he spoke eloquently of Sculptor Veit Stoss but not so much as mentioned the master's contemporary, Tilman Riemenschneider. It is true that the latter hailed not from Nuremberg but from nearby Wurzburg, yet all the qualities Hughes admires in Stoss's work can be found in Riemenschneider's extraordinary wood carvings. Riemenschneider was Stoss's equal, to say the least. John Rewald New York City Your review says Veit Stoss was not well known outside Germany. No one, however, could graduate from a Hungarian high school 40 years ago if, when presented with a slide of a wood carving, he could not distinguish whether it was a Stoss or a Riemenschneider. Vladimir Lieskovsky Woodside, Calif.