Is it permissible to sell Chinese goods as if they were Japanese, and is the money resulting from that unlawful, and would the share of the partner who rejected the idea also be unlawful?

If the spare parts are sound and sold at their usual price, then the sale is valid and the money earned is lawful.

It is not permissible to package parts and write names in other languages for the purpose of deception or misleading the buyer, as this is forbidden deception.

If the deception does not conceal a significant defect and does not increase the price, then the sale is valid and the money is lawful, and the sin is on the one who intended the deception.

If the deception conceals a significant defect or increases the price, then the increase must be returned to the buyer or given as charity on his behalf if he cannot be reached, and the sale is valid in both cases.

It is recommended to be truthful in selling and to clarify the reality of the commodity to the buyer, as the Prophet (peace be upon him) said: "If they are truthful and clarify, they will be blessed in their sale; and if they lie and conceal, the blessing of their sale will be erased."