Sorry about the hiccup of uptime around the event start. The game was down for about 18 minutes, but has been running fine since.
You are guaranteed to get fragments from Cosmos quests, and those fragments are either Precious Soul Fragments or 666 Soul Fragments.
While I was hoping we'd have everything squared away for communicating odds in time for the start of this event, there's still some questions we're looking to have answered regarding the new guideline, so I don't have any specifics to share yet.