I've used two of them, but the form only allows to select one diversifier. Just wanted to ask if this is intentional.

same thing, the form should be a checklist instead of radio buttons

Unfortunately, I’m currently working with itch support to fix an issue breaking the submission listing related to a change in these questions. I’m aware of the issue with selecting diversifiers, but I’d like to have the other issue fixed before making another change. For now, pick your favorite, and I’ll get it fixed as soon as possible so you can add the others later.