You actually can edit this. When you do ctrl shift X to mine a card with asbplayer, in the box that pops up, look for the pink line with the 2 dots at the ends. This is the sentence audio that will be recorded. Drag the dots around to capture more or less of the sentence audio. After you edit the position of the dots, click the check mark in the audio field and then the box will close, asbplayer will record again, and the box will pop up again. You can listen to how the sentence audio is going to sound by clicking on the field in the box that pops up. When you're satisfied with how it sounds, click update last card.
I am not at my pc right now and this description probably sounds confusing but I promise it makes sense when you're actually looking at it.