Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/stm32/stm32wl/STM32WL5x_CM4/RTC/CALR#0x0
CALR
Calibration minus
Calibration low-power mode
CALW16
Use a 16-second calibration cycle period
Use an 8-second calibration cycle period
https://github.com/modm-io/cmsis-svd-stm32