Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32h5/STM32H523/RCC/RCC_HSICFGR#0x0
RCC HSI calibration register
HSI clock calibration
HSI clock trimming
https://github.com/modm-io/cmsis-svd-stm32