4 seems to be the limit. You can have “6543”. Your real problem is the 7 out of order at the bottom.
You can do “4327” by typing 11,10,9,7, and setting the preference in the bottom panel to 'show compound intervals as simple.
For really complex figures, you’ll still need to use the Figurato font, which offers more flexibility at the moment.
I have to confess, this is a rather exceptional case, as Rebel wants a cluster of all notes. Still it would be good, if we could look up the possible limit, when it comes to inputting figured base with the setting “input literally”.
I spent quite a while trying to figure out, what my mistake was…