Custom theme with more than 8 colors

Custom color themes have been added as a feature but appear to be limited to 8 custom colors (white and black are fixed).  PowerBI creates 5 additional 'shades' for each custom color but these seem to be fixed.  Can this feature be enhanced to allow more than 8 colors?  Or allow the user to customize the 'shades' for each color (which would increase the total to 48)?