I can clarify what data is available in my tournament database.
The database contains only published tournament results - these are decklists and match records that tournament organizers make publicly available. For most premier events, this means Top 8, Top 16, or Top 32 finishers depending on the event and platform. Events from sources like MTGO (Magic Online) Challenges and Leagues, Melee-hosted tournaments, and MTG Top 8 aggregated results follow their respective publication standards. Smaller events may publish complete standings, while larger premier events typically only publish top finishers as you noted.
I don't have access to unpublished data from players who competed but didn't finish high enough to have their decklists reported. This is a limitation of public tournament data collection - if an organizer or platform doesn't publish a result, it won't appear in any aggregated database. My analysis tools work with what's been made publicly available through tournament results pages, official event coverage, and community aggregation sites.
If you're looking for data beyond published top finishes, you would need access to the tournament organizer's internal systems or player self-reporting, which isn't something I can query.
Sources: Data coverage reflects standard MTG tournament publishing practices - premier events typically publish top finishers only, while smaller community events may publish complete standings depending on the platform and organizer.