Hi
we found why this is difference from the predefined currency, as I told you before, that, calculated amount can’t be translated and currency sign always been there in left side for the limitation.
So In the input of donation forms, it will go to for checkout, and for the supporting checkout amount, Payment method, it’s required digits, So for this place, the currency sign always been left side, rules will be not applicable here.
Hope you got the point,
Best Regards