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Then, navigate to: HKEY_LOCAL_MACHINE/Software/Wow6432Node/Ubisoft/Might & Magic Heroes VI/Language
The value of the highlighted line should be as follows:

It works for me.
Try this (though it's unlikely to be there): HKEY_CURRENT_USER/Software/Ubisoft/Might & Magic Heroes VI
If it's not there either, then I'm at a loss. But the program should be listed somewhere in the registry...