Thank you very much @puzzlezaddict
I have that old post in EA France: https://answers.ea.com/t5/Autres-jeux-Les-Sims/Showtime-Envoi-impossible-via-simport/m-p/5646538,
about when the bug happened (with a photo there) if it can help understand. The translation is :
"Hello,
I've been searching for a solution for several days, but I still haven't found one:
I sent my singer Sim on tour to a friend who received it without seeing it. She canceled the tour, but on my side, my Sim returned, but the tour stage remained stuck. Since then, I have deleted this Sim hoping to resolve the issue, but my SimPort is still blocked, and nothing is showing up in the tour interface. I can't send new Sims, and all the tour stages are grayed out. It's impossible for me to cancel them on my end."
Since I got a new PC, I didn't keep any saves and deleted the Sim. Additionally, it has been so long that I can't remember which user I used for the exchange. Unfortunately, the problem still persists. I have just created a new save in Starlight Shore and selected the Buckshot household. The message says, "You have too many Sims on tour or awaiting reviews. If you don't want to wait, click on one of your Sims in 'Sims on Tour' to cancel their progress in their current tour and free up a slot."