Some protected DSK images won't load, probably needs more work since MAME has to convert the image to flux style data.
You could use the HxC utilities which includes an image converter, and convert the DSK image to MFM. This will also give the bonus of the new image being able to be written to.
As for Imperial Mahjong, the screen being offset to the right happens in certain games that use hardware scrolling (like Ghosts 'n Goblins, or Out of this World). I've mentioned it to Judge before, but it is a rather annoying bug.