The colors in the tree help to quickly find open clusters and to reopen problematic clusters.
Gray = At least one cluster has been completed here, but more still need to be processed.
Yellow = There is a ToCheck part here, which must be completed in any case.
But yellow beats green, i.e. if all clusters are completed (green), but there is a "To be checked" part in one of these clusters (yellow), then the folder is marked yellow.