2 bishops of the same color

mating with two bishops on the same colored square is impossible

Of course it's not impossible. It's unlikely, but not impossible. Using the OPs game as an example, he had two dark colored bishops and won on time. The two dark colored bishops, plus the fact white still had a pawn was enough to declare it sufficient material to win. Unlikely, but not impossible. One possible outcome could look something like this, and black didn't even need TWO dark colored bishops, one would be enough.

would be declared an insufficient material draw in this position

because the pawn is promoted to a knight, it would be a draw.

you can never find any other position where you win by solely two bishops on the same square while the opponent has a rook or queen

Except it wasn't. Which was his whole point. It was declared a win based on the opponent running out of time. Not insufficient material.

No, it would likely be a draw, but as we see it's still possible to checkmate if the opponent makes enough wrong moves.

Yes, but that's not what the OP was concerned about. His concern was that it SHOULD be insufficient material because checkmate can't be forced. The point is it's still possible to checkmate if the opponent makes enough wrong moves, thus, just the two dark colored bishops plus the opponent's pawn IS sufficient material. If the opponent promoted to a bishop, it's possible too.