I suppose one of the problems is that the label is used for the icon name. In FileSystem.php @ getImageUrl( $image_name ) I added some print() and I can see that the variable image_name contains the label (when I change it).
This could explain why there is no icon found in the file system. The icon “ah ah.svg“ exists, but the same icon with the new label(laughing) „laughing.svg“ not 😉
Could you please explain where the color setting is saved or how the color setting is treated?