Did you try country string patching? NeoGamma has it, but as you might know it has "some" limitations. I don't know if any other loader has it. It switches strings in the main.dol of the game, stuff like USA, EUR, JAP, forgot which strings exactly, not even sure it was 3 letters. You can manually patch this stuff with a hexeditor. Anyways, this patch does improve the region free capabilities for some games, especially japanese games, which i guess is the reason not too many people know about it. There's a chance that this will fix the problem, but it's not a high one.
Patching the main.dol is a complicated process, that involves unpacking the .iso, patching the main.dol and then repacking the whole .iso. There should be some guides somewhere for this kind of stuff.
If you disable the IOS Reload block or use a cIOS that doesn't support it, i assume the game resets the Wii instead of resetting the game if you select that option. If that's the case, that's why the language patch doesn't stay, it would need to be reapplied. With Generic Wii Patcher you can permanently patch the main.dol to another language. I'm 99% sure that the problem wouldn't be fixed by this.
Do you know that it is possible to change the region of a Wii? It's dangerous, so a lot of research would be required, but it may be worth it. Another alternative might be sneek, i think it allows to have an emulated nand from another region. If that's possible, it might be your best shot, but i wouldn't be able to help you any further.