If you want to get in touch with the organisers, you can do so through:
#guadec on irc.gnome.org - public channel, also used for IRC meetings
Telegram group, chat place at Telegram.
@guadec Twitter account.
Taiga Kanban board for task tracking
Or for private matters through:
firstname.lastname@example.org - private mailing list for the core organising team
You should normally use the public channels for contacting the local team.
These are pages related to the organization of the event: