I find choosing colours is about the hardest part of creating visualisations. And I am very pleased to see the importance of accessibility in the process. I usually end up sticking with colour brewer palettes but they have a tendency to end up looking samey after a while. I have been hoping that Adobe’s Capture app will help me out but it only generates a 5 colour palette, though maybe a combination of the natural palette as a starting point and your gradient technique will get me the colours I need.
Thank you for sharing.