Every Country has a Global Manager or User Responsibility to access Global SOB but it is supposed to limit users to their own Legal Entities. However, an Argentian journal can be posted by the Chilian user. How is this possible? 

This is working as intended. Security rules will prohibit a responsibility from being able to enter in certain values as well as prohibit the viewing of those values as well. However security rules will not prohibit the actions above because they are in the same set of books. The system does not determine if a journal has values in it that are blocked by security rules. If it did that, then the journal would appear as unbalanced. There would have to be an incredible amount of logic involved, which would further reduce performance, for the posting program to scan the journal for security rules first before posting. Posting does not take into consideration the rules, this is done at the time of journal entry .