A 12-day period is quite sufficient for registration.
After the topic was created, it was immediately moved to the Important section.
Information about the registration deadline was displayed in the tournament header, i.e., at the top of each page.

After registration closed, I added lists of cities to the templates for all participants, and those who "missed" the deadline could review them, which might influence their choices.

The draw is based on the rating.
Are you suggesting that we add those who forgot to register and re-run the draw? But that's not possible because one match has already been played, and some games are already in progress.