Customer wants to load the tax assets in USD by FBDI in the FA_MASS_ADDITIONS and FA_MC_MASS_RATE

Summary:

The user have corporate Book associate a primary ledger of GL in MXN currency.

Have a Tax book associate a secondary ledger of GL in USD currency.

The client wants to upload the assets in USD in the tax book by FBDI in FA_MASS_ADDITIONS and FA_MC_MASS_RATE, while the system thinks that they are in the functional currency MXN.

Can this have any impact on the functioning of the module?
Why is it necessary to enter the data in the functional currency MXN in the FA_MASS_ADDITIONS sheet? and only in the FA_MC_MASS_RATE in USD?