Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wl/STM32WL5x_CM0P/IPCC/IPCC_C1TOC2SR#0x0
IPCC processor 1 to processor 2 status register
CH1F
CH2F
CH3F
CH4F
CH5F
CH6F
https://github.com/modm-io/cmsis-svd-stm32