Hi,
So you can add a new articulation into the collapsed lane with the pencil (draw) tool, which can also be temporarily activated from the object selection tool by using the ALT key on Windows or probably CMD on MacOS. Click in the collapsed group at the right spot to add the new articulation.
This will of course probably not add the exact articulation you want (because you can only choose the group when collapsed, so it will make a guess of which articulation you might want from the collapsed group), but there is a drop down menu for each articulation when in the collapsed state on the right hand side that lets you change it to any other articulation.
Clicking on the left edge will open that menu and let you change the articulation to something else.
Adding a new articulation (which will be wrong) and changing it to something else can be done pretty quickly if you get used to the dance of ALT-click to create a new articulation and then click once more without ALT to activate the drop down to change it to the one you want.
You can also use the scroll wheel of the mouse to change articulations when in the collapsed state without activating the menu. This is not typically useful for large groups with a lot of options but can be useful for smaller groups.
In Cubase 15, I’m basically working 100% of the time in the new way, with the groups collapsed and never expanded.