Kévin, you may believe you are beating your head against a stone wall right now, but you are not. The people who have answered your question are the right ones to speak with. They are responsive and very involved in massive improvements to the site. Ian Beacall invited you to work with him. This is a generous offer and one you should jump on enthusiastically. I would if I had the skill and ability I hope you have.
It's not that we are hiding anything, it's more like WikiTree has grown explosively and while we are thrilled, we have a small but growing team of volunteers keeping up. You have been invited to join them. Hop on board - and welcome.