Gardner,
I’m a member of two US based forums, to be honest they fill me with despair for the electrical trade as a whole.
I’ve had it suggested a high Ra is desirable as it limits fault current. They weren’t happy when I mentioned a rise in potential touch voltage, they became very defensive.
Multiple ground electrodes are a waste of time and money.
You’re making units for export, do you really think an internet forum is the place to get concise information regarding wiring regulations? If a unit arrives in the UK it will have to be connected by a UK electrician. If the electrician is competent he will test the unit to BS7671. Any deviation and the whole unit will need attention, which is going to be very expensive for you.
You’re running this as a business, therefore get a UK consultant that will carry the can when things aren’t compliant.
Personally I’d tie a label to it marked “return to sender”.