Just to confirm that is OK, if you escape manually the pipe on the gradient, as your second example:
note as MYNOTE
|<back:fuchsia\|white>Val A|Val B|Val C|
We only observe a slight shift.
Then, you can change your request on a wanted feature in order to ask to escape the pipe with \ if the pipe is within the value of a gradient on a table!
A workaround will be to does not use |, but more / or \: the result is very similar...