i think i know what the problem with these out of region games booting to a blank screen is.
on wiikey2 when you put the Region patch to on it patches the screen output to the region of the initial game that you first booted after you installed the modchip, this is the problem as many out of region games refuses to boot when screen output is forced to (PAL, PAL60, NTSC ect)
however if you decided to disable Region patch on the wiikey2 using the config disk then you would find that out of region games would refuse to even be detected in the disc channel, this is becouse the wiikey2 REgion patcher does two things when enabled, first is the problematic one, force screen output, second is the one that is needed, Patch Game boot region, unfortunately there isn't any way to enable one and not the other, hopefully Team wiikey well add two option on the new update.
the only way to boot these problematic games is to use a combination of wiikey2 + gecko OS or Backup loader.
first disable the region patch on wiikey2, then load HBC then load gecko OS or Backup loader in the option on these loader don't force video output have all set to off, then load the problem games, do not reboot with Hooks as this would give the same result as booting with the using the disc channel.
if like me you get a RED screen on you PAL wii then if using a RGB scart cable then on your TV option turn off RGB and it should fix this, if in the USA then simply use component, this should fix it.
on my wii system menu 3.2 MK and SSBB do not boot when i use the disk channel it boots to an blank screen so i have to use backup loader to boot it and it works fine, good thing about using wiikey2 + gecko OS or Backup loader is the modchip forces games to load at 6X.
hopefully TeamWiikey fixes this as on the modchip feature it stated that it works on MK and SSBB, but for me it don't and to make it even sad my original of SSBB don't even boot.