Hi Eve,
I agree that we don't need the diagram type, however the Toolbox name would be useful.
For SysML, the Namespace is SysML 1.5 and the group names are SysML Block Definition, SysML Block Internal, etc. In this case, it works because the groups are somehow named after the toolbox e.g. SysML Block Definition is under the BlockDefinition toolbox.
For a custom MDG, if you make the choice of applying the same grouping names for all toolboxes e.g. "Custom Elements" and "Custom Relations", then there is no way of knowing which one to select within the "Pinned Toolbox Pages" window. Introducing the toolbox name between Namespace and Name columns would sort the issue in this case.
In the problem you mention, worst case scenario, you have a toolbox name with the same value as name, yet it will be consistent with the names available from EA: I select a toolbox, and I have a list of groups.