It's number of houses, barracks, fields and civilizations and has nothing to do with the second line.
In the second line are only the gather rates (incl. way) lined under and attached debugging info for me. The last % is the gather rate in relation to the maximum of 5.8.
The replay file is written instantly. When spectating a live game I regularly use it to check out the replay to see which player uses quickstart, which some players use in even in rated 1v1s.
I think it would be a great analysis tool, like a chess engine (although this wouldn't cover all strategies). But chess engines are also used for cheating. So I'd rather have no analysis and no more added cheating than more analysis incl. more cheats.