The users Access Tos granted by the Administrator allow the user to view the Accounts, Journals, and Reports by going to them directly or by using the F9 (Journal/Ledger switch) key.
The pick root is currently set by the user (not the administrator) which is leading to the confusion and the encountered bug when changing the pick root when you enter the books as that user. All the accounts do appear when you press F3 to pick an account which does let you post to the account but if it is an account that the user does not have access to (Access Tos table set by the administrator) you can not view the cross account (F9) as access is denied.
In 2.09, there will be some extra options for the user on the user Access Tos table for the pick root which can only be set by the administrator (or a user with administrator rights) and a Preferences table (perhaps under File > Preferences) where the user can change items about ones self that are logical and do not breach security. I have the programmers looking at this.