revised question on penalty during touchdown

[Bill D]

You are correct. A gets the TD AND may take the distance penalty at the succeeding spot, which is the try. In your example, it is half the distance on the try. While that may not seem to be much of a penalty, that's the rule. Prior to last year, the rule was that when A scored a TD, the foul was declined by rule. It was felt that may allow for "cheap" B fouls, hence the change.