In the unstable branch, click on "might" in pane 2. In pane 4 you see might --> have --> [been (0.5), not (0.5)]
Level 2 is drawn as a box with two items. This is unnecessary; we have plenty of room to draw 2 nodes at level 2 instead of collecting them into a box.
Click on "must" and get "must" --> "be" --> box with four entries. We don't need to box this; there is plenty of room to make separate arrows. Start boxing at 5 or more entries.
In the unstable branch, click on "might" in pane 2. In pane 4 you see
might --> have --> [been (0.5), not (0.5)]
Level 2 is drawn as a box with two items. This is unnecessary; we have plenty of room to draw 2 nodes at level 2 instead of collecting them into a box.