Clarifying meeting hour value

Hi VI_Migration, I can't speak to the Teams Admin Center but here is the definition of how meeting hours are calculated within Advanced Insights: Number of hours the person spent in meetings with at least one other person during and outside of working hours.

If the meeting was on the employees' calendars for 1 hour and both accepted and attended it would register in the Person Query as 1 meeting hour. 

Attendee meeting hours would be 1 hour * # of attendees, yes that is correct. Here is the definition of attendee meeting hours: Total number of adjusted meeting hours for all attendees.
A meeting query focuses on the meeting as the main entity and reports on the various meeting attributes; a person query looks from a person's perspective and aggregates multiple meetings for the selected time period. Because the two query types have different purposes, their output also differs.

You can also refer to this document: Metric definitions | Microsoft Docs