It struggles a little with complex positions, like when there are an even number of moves and it has to round down, but when run against itself it’s capable of finding some novelties. At one point I saw six knights on the board at once; Stockfish rarely exceeds four.
He mentioned that it rounded down when even, so I’m assuming it went forward one place.
Also, wouldn’t checkmate be notated with #?
You’re right, “#” for checkmate is in more common use than the “++”