Hi, Shal. Thank you very much for putting together the GMF wiki page about notifications! (And thanks also to others who've contributed revisions to it.) With Mark's agreement, I've been holding off on updating the Help Center resources until the dust settles. (If I'd started sooner, it would've been like changing tires on a moving car. :-) ) I plan to start on the Help Center updates this week, and the wiki page will be a huge help.
In general, the info on the wiki page looks pretty good to me as far as I currently understand notifications. Regarding the terms "Group Notice," "Member Notice," and "Moderator Notice": I agree with the categorizations, but I'm a little concerned that "Notice" (especially "Member Notice") could be confused with references to the member notices that owners/moderators set up in their groups' settings. Perhaps using "Notification" here, rather than "Notice," would help alleviate potential confusion.
As a further distinction, throughout the wiki and the Help Center documentation, maybe we can try to use "notification" to refer to the alert message that is sent by email or web/app push and "notice" to refer to the message content (the details of what someone is being notified about). I could add those terms to the glossary. (I already intended to add "push notification.")