The hidden menu doesn't work all the time on vWii.
be sure to have the font.bin or it will not work at all, then don't try to open the menu right after system menu is loaded, wait one minute before trying to display it.
sometime it's even flickering on the screen, it's very unstable.
Ahh, I remember about the garbage text. It's an option in USBLoaderGX for Wii games (I don't know if there's the same option in neek). It's the "country string patch" option in the game settings.
You don't need neek for most games, just use Full emuNAND option instead.
There's a known issue with the settings and patches not working with the channels. Maybe that would have fix your issue.
You can still try, it might work.
use emuNAND full, enable country string option.
if it does nothing, go to settings>loader settings, look for the channel launch mode, switch from normal<->boot.dol
if it doesn't work, you can try Wiiflow, the settings and patches are working with channels in that loader. (just to see if it fix your issue)
Ugh, and emuNAND doesn't seem to want to display in the WiiFlow mod... Though I can switch to the neek system menu via that. So that's good. Even though I can't enter this hidden menu you're talking about, even with the font.bin. But eh, again, the garbled text isn't the hugest issue in the world, and it's only problematic on a handful of games and the display of titles on Japanese Virtual Console channel banners (which don't display text at all, instead of just garbled text). Or, for that matter, the display of some channel banners in general is a bit weird, like the layering's wrong.