I’d look for something in the manual of the Genos for a single channel that ‘mirrors’ the layout of the Genos’s own keyboard. Many arrangers have this ability.

Your main issue with splitting the Roland is that each Upper and Lower and MBASS Part in the arranger will have its own channel. So you are faced with the issue of setting up programs in the RD for Lower to arranger, MBS to arranger, Upper to arranger UPR1, UPR2, UPR3, and hand select if layered. Then you’ll have to make sure that the Roland doesn’t send PC changes, sends bender or after touch when needed, doesn’t send them when not, or enable or disable them on a per Registration basis in the Genos.

If the Genos has a dumb ‘one channel mirror’ mode, life will be a lot less complex...