Picking a Pattern for a Meeting-Notes-to-Action-Items Feature

Product wants a feature: given a meeting transcript, produce a list of action items, each with an owner and a due date if one was stated. Most transcripts state owners and dates explicitly ("Sam will send the doc by Friday"); a minority reference something like "the usual review cadence" or "whoever's free" that requires checking a team calendar/roster tool to resolve into a concrete owner or date.

1. Using the worked support-ticket example's reasoning as a template, propose a production design for this feature — which pattern(s), and how the minority case is handled.
2. Estimate, in the same relative terms as the worked example's table (roughly how many times more expensive/slower), how your design's cost compares between the majority and minority cases.
3. What evidence would tell you your initial split between "handles it with the cheap pattern" and "needs the expensive pattern" was wrong, and what would you do about it?