Learned it here [Check_mk (deutsch)] Performance Data gezielt löschen
For CRE there is a way to delete the rrd files from the folder. This at least solves the biggest issues.
But still: There is a mix of separate views of each metric and combined views (all in once). And color definitions are not recognized in the combined view. Ordering is also nuts…
And why an integer counter needs to have an average will remain the secret of CMK…