Thank you for this, seems like this is the go-to method for importing Wii U games without having to modify the .rpx filenames. Still takes a bit of work, but at least there aren't that many games for the Wii U. My process went as follows:
1. Import at least 1 game for Nintendo Wii U into LaunchBox.
2. Edit game folder names so that they don't include special characters such as ® and ©. I kept a list of the original folder names in a separate text file.
3. Import the games into LaunchBox using the plugin. Make sure the number of games imported matches up with the number of game folders you have.
4. There are a few games with multiple .rpx files, for me these were "Skylanders SuperChargers" and "SpongeBob SquarePants Plankton’s Robotic Revenge". Remove the duplicates from LaunchBox.
5. Change the default emulator for all games to Cemu.
6. Since the plugin doesn't import Japan and All regions, create a playlist and filter for Wii U Japan games, then bulk edit all games and add Japan as region. Do the same for games with the region All.
7. Remove the initial game that was imported before the plugin, then re-import it using the plugin. Or just manually edit the metadata so that it's consistent with the other games.
8. Select all games and fetch media artwork.
9. Rename any changed folder names back to their original folder names.
10. Exit LaunchBox. Edit "LaunchBox\Data\Platforms\Nintendo Wii U.xml" and change folder names in paths to their original folder names.
Note: DO NOT consolidate games, since not every game will be consolidated due to the awful naming scheme and result in a messy collection. This is the only downside to Wii U games, so you're going to end up with duplicate games and artwork for each region.
EDIT: Just a heads up before anyone spends time trying to import .rpx into LaunchBox. Seems there is a new format called .wua which is better than .rpx and combines everything into one file, which would make importing a lot easier. However, this Cemu release (v1.27.0b) is only experimental and has a bug which doesn't detect paths with special characters (ie. Super Smash Bros. or all the DLC/Update folders which have a dot in their names). So until this gets fixed there isn't an easy way to convert to .wua.