Just to keep everybody subscribed to this topic informed of our current status:

While we initially planned to use Artio BookIt and where almost ready to ask Artio Developers to add the frontend editing features for us as a custom extension, we have now switched to another Booking component that already offers frontend submission, together with a multi-vendor approach that allows us to also charge commissions on items booked.

So we will no longer need the discussed frontend editing extension for Artio Book It.

Thanks,
Sebastian