The Inner Tree Evaluator Node section has the following line:
Any information collected or set by the parent tree, for example, a username or the authentication level, is available to the child trees. Information collected by child trees is available to the parent once evaluation of the child is complete.
Which is not true for passwords - they're not reflected in the transient state of child trees. When trying to authenticate a user within the child tree by retrieving the password from the parent tree, I see the following error:
This is a valid limitation, but it should be listed in the documentation along with some best practices for implementing the node as seen in the AM-400B-FR-SG coursebook (page 151 and 489).