First off, explain this: Why do you want to downgrade your Wii?
Do you realise that there is
ABSOLUTELY NO BENEFIT to doing so? And that there is
NOTHING you can do on 3.2 that you cannot do on 4.3?
Anyway, the error is because the vulnerabilities in IOS that are used by AnyRegion Changer (ARC) are no longer present in any official IOS. ARC has never been updated for several reasons. First and foremost, it is UNNECESSARY. There is no reason or merit of downgrading the Wii. On some consoles it makes sense. Not the Wii.
The only thing that would ever be vaguely sensible to downgrade is an IOS, but even that is not necessary.
tl;dr - Don't downgrade your Wii. Chances are you'll brick it (i.e. completely broken, not functioning AT ALL), or at least leave it in a volatile state, ready to brick at the slightest mishap.
And your Wii is NOT semi-bricked. ARC not working is not a semi brick, or any sort of brick. A semi-brick is when you cannot access the Wii Settings menu from the System Menu.