Muyou wrote:
Traxler counterattack is flawed in my opinion if white defends properly.
If Black doesn't take d4 with bishop, instead he takes with pawn or knight, then the bishop will be blocked and white can take f6 freely and traxler counterattack will not happen. So arguably Black's best move after d4 is d5, and it will be rather equalized a position.
Black could (and should) meet 5.d4!? with 5...d5, as you mentioned.
Buecker's analysis of 5.d4 is freely available since a decade ago. I doubt that Black can equalize (Buecker too).
In your analysis, the move c2-c3 does not help white- he is better without it, since the knight can occupy c3:
Black has not enough for the sacrifised material.
Traxler counterattack is flawed in my opinion if white defends properly.
If Black doesn't take d4 with bishop, instead he takes with pawn or knight, then the bishop will be blocked and white can take f6 freely and traxler counterattack will not happen. So arguably Black's best move after d4 is d5, and it will be rather equalized a position.