Hi everyone - I finally figured out the weird syntax that sheet summary fields require for sumifs courtesy of an answer to one of the questions for a different user, but I still can't get my formula to work.
=SUMIFS([Planned Expense]:[Planned Expense], [Event Type]:[Event Type], @cell = "Moments that Matter", [Event past]:[Event past], @cell = "current"). It would also be helpful if I could get this to work:
=SUMIFS([Planned Expense]:[Planned Expense], [Event Type]:[Event Type], @cell = "Moments that Matter", OR([Event past]:[Event past]= @cell "current",[Event past]:[Event past] = @cell "future")