After testing the process in announcement, and comparing it with the one with member form (which is just perfect) we think being directly redirected to the edit form when we have the right was a mistake.
Whatever the rights, when we click on an announcement we access the view form
An edit button is displayed on the top left (same position than member form) if we have the rights.
The mistake is ours here, we know it, don't make it a priority.
After testing the process in announcement, and comparing it with the one with member form (which is just perfect) we think being directly redirected to the edit form when we have the right was a mistake.
Whatever the rights, when we click on an announcement we access the view form An edit button is displayed on the top left (same position than member form) if we have the rights.
The mistake is ours here, we know it, don't make it a priority.