Feature groups
Axs far as no colour has been assigned to a feature group, the feature group is NOT a basic OSM feature group (level-1 key).
Instead it is a feature group that has been introduced by ENAiKOON for an optimal grouping of the map features which allows as fast as possible finding an appropriate map feature template while mapping a new map feature.
In case you are missing a map feature group please send an information to Markus