Thanks a lot for all your replies and edits, I learned a lot.
So I will use ‘preserve chrominance = no’ as default, and finetune with ‘white relative exposure’ and ‘highlight reconstruction’ when using max RGB.
But I still have no clue why there is such a difference between legacy-wb and color calibration.
What does ‘wrong WP’ mean? How can I ‘use the canon values’?