You can try and convert the files back into wav files that is possible what is looked for in the cue file, but as above there will be quality loss, but then again that should not stop it from working
P.S. that game is officially translated and is part of he PSP Castlevania: The Dracula X Chronicles as an unlockable game, also has a very nice version of Symphony of the Night built into it again unlockable (it's the PSX version with some nicely added features, like the Jap Map layout (including the two extra familiars) options of Jap or Eng Voices and text), Maria is also playable (This is also a re-voiced/translated version though the translation is no more accurate than the original [I like the voices for both versions myself, but if that does bother you just switch the voices to jap
]), as well as it being a remake of Rondo of Blood in itself that is rather cool and fun