I will do it with the shelves it’s a more librarian way

The only downside is the need to remember that the shelve has to have only one item (I don’t know what will happen if two images have the same LastReadDate and ReadStatus).
I tried with contentType=6 etc, but it turns out to be a loop as I need to update all image before updating the chosen one at 2030, 1. Hence updating the others triggers the trigger and all images are updated. Couldn’t do it without the possibility of alter the trigger or change the new value, which is not permitted.
Thanks for your advices!
EDIT : firsts tests are ok,
moving it in dev corner.