A lot of people still have trouble with Wii Party U. I've did some more testing with this game and here are my results for making it more compatible with Loadiine 4.0.
Optional: make it compatible with European consoles
Wii Party U has only got a USA scene by PoWeRUp so most Europeans must first rename some folders to make it compatible. The curious thing is that some European language files are present on the USA disc, but not all of them. So where available use your own language and rename them as follows:
Rename content\common\mess\US_English (or French or Spanish) to content\common\mess\EU_<yourlanguagelong>
For example: EU_Dutch, EU_Russia, EU_French etc.
Rename content\common\movie\EU\en to content\common\movie\EU\<yourlanguageshort>
For example: du (for Dutch), ru (for Russian), it (for Italian), ge (for German) etc. (French and Spanish don't need a rename as they are already there)
Rename in the folder content\sound\common the following files:
NEXPY_SOUND_US.bfsar to NEXPY_SOUND_EU.bfsar
NEXPY_SOUND_US.fsid to NEXPY_SOUND_EU.fsid
NEXPY_SOUND_US.xml to NEXPY_SOUND_EU.xml
If you made a mistake in renaming the files, Wii Party U gives you nice error complaining about error 150-3034 but it won't freeze the Wii U and you can go back to the Wii U menu. Just take out your SD card and correct the error, or use Loadiine server mode to find out which language name it is expecting.
Speed up the loading times
To speed up the loading times a bit and to save some space, you can delete the other languages besides your own language the Wii U is set to in all the above mentioned folders. You can also delete:
content\sound\JP, or US, or EU depending on your country/language setting. Also in the these folder you can delete the other languages.
Fixing the Space Zappers Minigame
There is a big incompatibility with Loadliine and Wii Party U that isn't mentioned yet in the Loadiine compatibility list. The mini game Space Zappers won't work. It is especially annoying when the game pops up in the one of the TV Party mode games, because it will hang the Wii U completely! I've spend some time figuring this out. First the PoWeRUp release will hang at loading:
content/common\ch_base/pc/mot/spg_idle01_w.bnfmsa
This file isn't available on the PoWeRUp release. Also with copying and renaming the available spg_idle01.bnfmsa to spg_idle01_w.bnfmsa won't make a difference. I first thought the PoWeRUp was inproper, so I downloaded to complete game from NUS (using the title.tik from the PoWeRUp release). With using the NUS files it will hang at the following file:
\content\common\bin\nmg418.bin
So there is something wrong with the PoWeRUp release, but it doesn't make a difference. I've even tested it with multiple SD cards and in SSB and Mii modes. My temporarily solution is to copy and rename the files of another mini game to have a working TV Party mode (with the chance that you get this mini game twice in one game). You can do that by taking a choosing a mini game file in the folder:
\code\nmg<number>.rpl
For example nmg420.rpl. Copy it to the same folder and rename it to: nmg418.bin (let it overwrite nmg418.rpl or delete it). Than go to the folder:
\content\common\bin
Delete: nmg418.bin, nmg418.usen.bin, nmg418.usfr.bin and nmg418.ussp.bin. Copy your nmg<number>.bin, nmg<number>.usen.bin, nmg<number>.usfr.bin and nmg<number>.ussp.bin into the same folder and rename them to nmg418.bin, nmg418.usen.bin, nmg418.usfr.bin and nmg418.ussp.bin.
This is all that is needed to prevent Wii Party U to hang. You still will see Space Zappers as intro and instruction, but when you start the game another minigame is started. If you wan't you can rename these files in all the other folders to also see the right intro screens, but it isn't needed to have Wii Party U working.
Unresolved: wrong selection in GamePad Party
There is still one issue left; in the GamePad Party mode you get another selection than what you have pressed. Everything is working, but just the menu selection is off. This happens with the PoWeRUp release and the NUS download. So I think it is a Loadiine compatibility issue. Maybe it can be solved by renaming some files, but I didn't care to look into it further because it isn't bothering me.
I hope I can help a lot more people playing Wii Party U with these instructions. Also the compatibility list needs to be updated with this info, because there are some issues with Loadiine. Can I edit it to link to this post?