I would like to suggest making it possible for SIGs to use ticket labels for marking tickets of interest to SIG members. I have labelled the present ticket with "LingSIG" to illustrate that. I do hope that this is an uncontroversial suggestion. Thanks for considering this.
Implementing this suggestion could be done in several ways: the project admin might create a user group "SIG conveners" (Admin|User Permissions|Add a new group) and then add this group to groups that can edit tickets (Admin|Tools|Tickets|Permissions|Update(?)). Or they can make SIG conveners "Developers" and make sure that this predefined group can edit tickets. Or, finally, the least maintenance-friendly option: add users to the "Update" field by name (I do hope it's the "Update" field -- the documentation is delightfully vague on that).