In https://github.com/mapillary/mapillary_tools/tree/master/python there is a script which will write a direction based on your tracel direction. You can also tell it that the camera did not point forward and it will correct for that.
There is no tool to just adjust the direction - I don’t know if it is possible with exiftool.
If you would like to run the script and needs help, we have the thread Page not found for that.