The Room (Site) of a ticket determines who wants that ticket to get fixed and who is going to pay.
We need a new model "X" which links a user to the sites for which they can report tickets.
We need a new field "assigned to" and remove that notion from votes (because unlike Lino Care we want to have one and only one responsible user per ticket).
Topic (Component) and Mission (Project) are optional and experimental even for us. (NB: e.g. tickets having mission avanti must get assigned to the site avanti)