It looks like I've found something interesting. Remember we talked about the host/client score difference before? Well, there is a clear pattern in this difference.
Let's take our real final score and the result screen score of yours (as a client).
The real score:
1P: 225 793
2P: 210 090
The client score on the result screen:
1P: 257 020
2P: 241 682
For some reason while rewatching our play I found something weird in this difference and decided to merely detract all the bonuses we receive at the end of the game ( time + life + star ) from the client score on the result screen. But first, let's see how much we gain by being a client.
1P: 257 020 - 225 793 = 31 227.
2P: 241 682 - 210 090 = 31 592.
That's how much you got by being a client.
And now let's sum up all the bones to see what they amount to.
1P: 27 092 + 4 385 + 250 = 31 727.
2P: 27 092 + 5000 + 0 = 32 092.
Eureka! You can see that by being a client the game sums up the bonuses TWICE minus 500 points for each player! Why is that I have no idea but at least this pattern can be seen in any 2P online session.