Roadmap:

• Research: How are they obtained?
• Research: Do they need defeat detection?

Possibly related: #67

I've looked over the ingame events. Not just for BfA, but in general, and here is my conclusion:

• Noblegarden (0 items in database, 0 rare items, 0 items missing)
• Children's Week (0 items in database, 0 rare items, 0 items missing)
• Lunar Festival (0 items in database, 0 rare items, 0 items missing)
• Midsummer Fire Festival (1 item in database, 1 rare item, 0 items missing)
• Love is in the Air (3 items in database, 3 rare items, 0 items missing)
• Hallow's End (3 items in database, 3 rare items, 0 items missing)
• Brewfest (2 items in database, 2 rare items, 0 items missing)
• Pirates' Day (0 items in database, 0 rare items, 0 items missing) NB: One 90% drop rate item not added.
• Pilgrim's Bounty (2 items in database, 2 rare items, 0 items missing)
• Feast of Winter Veil (34 items in database, 34 rare items, 0 items missing)
• Day of the Dead (0 items in database, 0 rare items, 0 items missing)
• Harvest Festival (0 items in database, 0 rare items, 0 items missing)
• WoW's Anniversary (0 items in database, 0 rare items, 0 items missing)

Total 0 items missing.

Hmm. I thought they converted some items/added new ones, but thanks for checking!