Hi Laurence,
We have validated your reported scenario. As of now, we do not have support to customize data labels. We have already logged a feature request on this. Based on other logged tasks priority, this feature will be included in any of our upcoming release. You can keep track of the feature from the feedback portal below.
If you have any more specifications or suggestions to the feature request, you can add it as a comment in the portal.
Kindly revert us if you have any concerns.
Regards,
Durga G