As 4×100 won the fifth round (except for the Smart Random player, who’s almost undefeated), I played a game against it to see how it’s doing.

The first move is in column 2, which isn’t bad. The first player can force a win or tie with perfect play, by beginning in the center column; the AI seems to be gravitating towards that.
For the rest of the game, it pursues a vertical column with single-minded devotion. Unfortunately, it began a new column, instead of continuing from its first piece.
Also, it hasn’t yet learned to block plays by the opponent. I was able to win by playing straight out from my initial piece.
Overall, rather disappointing, but the network is still quite young. We’ll see what happens as they train.