Cut and paste this URL to share the unmodified register and value:
https://regviz.com/r/Renesas Electronics/R7FA6T1AD/CAN0/TECR#0x0
Transmit Error Count Register
Transmit error count functionTECR increments or decrements the counter value according to the error status of the CAN module during transmission.
https://github.com/cmsis-svd/cmsis-svd-data