First speech in the second session

Practically speaking: each item on the agenda = one abstract entry. Group “Tuesday/Wednesday” by day taxonomy (or by programme date). Sections “SESSION I…VII” are grouped by session. The column “Danka Auditorium / room 347…” is grouped by room.

“Time” with programme-start + programme-end. “Duration” with programme-duration. You can keep “Moderator” at the session level as a field in session positions (or in the future as a separate “session” type, but here we stick to your condition: expand the existing type and maintain backward compatibility).