Thank you for that information. I have a better idea of what you are trying to do, unfortunately, there isn’t a setting in the MAP Tagger tool that allows you to change it to the left alignment. The quickest way to change your labels is to Select All of them in the Layers panel, and then in the Paragraph panel (Window > Type > Paragraph), and then selecting the left align option.
If you mean something by “flush left” can you email us at email@example.com and show me an example with a screenshot? If that is what you want to do, then I can file a feature request to include left alignment within the MAP Tagger tool.