When I try to change "shop home" or "categories" or "view cart" for russian letters i get message "a page already exists with that name", can I do it?

I am sorry Dennis but our software does not support the ability to use Russian characters at this time.

I am using both free HTML editor and free Menu Builder. I have just placed an order for the Pro Menu Builder.
I have read both the tutorials for both products.
I downloaded Iconic Red and imported it into a test website.
I have not been able to figure out how to change any of the menu titles or add pages and
have not found any material in the tutorials that would seem to apply.

Thanks for your help.

David Wright Sr.