> All I get is a black screen... Does the SM RPG cart only work on a US console??
Pretty much yes, a US SM RPG cart only works on US console unless you have a custom built import converter.
SM RPG uses an SA1 chip. The SA1 has a built-in CIC lockout chip but unlike most normal chip games the SA1 lockout is two way. That is, unless it communicates with the corresponding lockout chip on the other side (normally the SNES deck) it will lock out the SA1 and you can't do squat.
I would guess that most import converters (PAL->US) just have their own PAL CIC chip inside which works spiffy keen for normal games that only use one way lockout but will never work on SA1 chips. The import converter would need to have two lockout chips to work with an SA1 game: a PAL CIC on the PAL SNES side to unlock the SNES and a US SNES console CIC on the cart side to unlock the SA1.