♣The true name is not "CastellóN", in fact that doesn't mean anything (just it "sounds" as this name were in Castilian language, as well as you'd say "Benicarló-N" or "Mataró-N"). "Castelló" means "Little Castle" in Catalan (Castell = Castle, -ó =little). Castelló is no Castilian town, but was funded by James/Jaume I (a Catalan King by fathers' line, who issued Castelló Charter from Lleida, 1251, Catalonia, and a 90% of settlers were Catalonians in according to the "Llibre del Repartiment").
Visit a square at Guitarrista Tàrrega-Mestre Ripollés, next Conservatori where is a little sculpture of Na Violant d'Hongria, in Castelló, to see and read it.
In the U.S. didn't change "San Francisco" into "St Francis" neither "Palo Alto" into "High Stick" in California, e.g.
So, Castelló is the is the original name, as much as the Kunta Kinte's one ツ