In our OSD image we utilize the _SMSTSLastActionRetCode for error capturing. This helps us identify in the log where the image is specifically failing, but it doesn't provide very much value to the technician performing the image.
It would be nice if there was an additional variable of _SMSTSLastActionName, which passes the task sequence steps name instead of the return code. This would allow us to display a prompt with the action that failed in addition to the failure code.
Thanks for all your suggestions and feedback, updating status to completed. This was actually completed in 1810 release, my bad for not updating.
SCCM 1902 fast Ring released today
This should be marked as completed as of v1810.