The Roland SD-50 appears to have very similar endpoint properties to my EDIROL UA-4FX and UA-25EX. This makes me think you could try adding this to the capture quirks table, although I'm not sure if it would override the new automatic configuration method, Takashi left the table there for fringe tests so it should:
IMPLICIT_FB_FIXED_DEV(0x0582, 0x0114, 0x01, 0x01), /* Roland SD-50 */
My guess endpoint address of 0x01 (just after the 0x0114) could be wrong, but since the R-26, INTEGRA-7, etc. OUT endpoint address is used, that's the one I chose for yours. Truthfully, I had both the EDIROL UA-4FX and UA-25EX running with the plain wrong address of 0x0d (which was meant for other devices) and they were working perfectly.
I hope that helps,
Lucas