What kind of fees would be charged to register a used right-hand drive car imported from J
The registration fees would be the same as any used car and that varies.
However, getting a Japanese car (or any car imported to the US that was not built to US requirements in the first place) in compliance with the US safety and emission regulations may cost thousands or tens of thousands of dollars.
Actually you should worry about some other fees and rules. Importing a car to US can be pretty hard. But I recommend this trusted broker https://clearitusa.com/