Don - KM4UDX
There was so much trial, error, fumble, confusion and general stupidity in my process that it is a model of what not to do.
I distill till the process:
1) express the 10mhz freq error as a percent delta
2) apply that percent delta to the weird calibration number in memory manager, reboot
3) remeasure the error (a) if close enough to step 4, (b) if still to far off go to step 1
4) run WSJT-X freq calibration process and apply proposed adjustments
5) if your WSPRnet spots still work at all, consider yourself lucky, if you get lots more spots consider yourself very lucky.
This process took me hours and hours to develop and implement. I recall reading about this exact process in one of my late night uBITX reading deep dives. But I didn't just implement it. No, I had to invent it on my own at great expense.
So as usual, I have discovered what others have known all along.