"La torre del mecanismo" actually translates into "The mechanism tower" or "The mechanical tower" (which is the name of the Clock Tower in Order of Ecclesia).
And usually, 'mechanisms' have some kind of clockwork devices on them, so it's not much of a translation error.
"Gear Tower" would be in Spanish "Torre de Engranajes" (which is really "The Tower of Gears"... which is the Clock Tower's name in Castlevania Chronicles/X68000).