IIRC, the 'ega' device in MAME is a rewrite that Judge never actually finished. In my experience it doesn't work as well as the EGA backwards compatibility in the 'vga' and 'svga' devices, which use the older pre-rewrite code.
I'll have a guess at the possible cause of the green tint. A real EGA card uses 6-bit colour (RrGgBb) for 350-line modes, but 4-bit colour (RGBI) for 200-line modes. Pin 6 of the connector is 'secondary green' in 350-line modes, but 'intensity' in 200-line modes.
So I suspect that the game has set up an RGBI palette, but MESS is rendering it as RrGgBb.