Unfortunately, the garlic mustard has dropped seed for however many years it has been growing on the two acres. Those seeds can remain viable under the soil for at least ten years, so you need to keep pulling the plants and preventing them from going to seed, until the seeds in the soil have been exhausted. Fortunately, if you don’t bring the seeds to the surface, they might never have a chance to germinate. But, when you pull the plants, that can bring the seeds to the surface. So, it just takes long term dedication. It can be a huge job. I had a similar situation that I worked on for four years before a job transfer took me away from the property. I found the garlic mustard pulling somewhat therapeutic. But, I also succumbed to using weed killer on zillions of microscopic sprouts that showed before the native wildflowers sprouted. Good luck.

You can do a controlled burn. It will kill a lot of the garlic mustard, especially the little, young plants. It would be best to eradicate all the invasive shrubs before planting desirable plants in there.

https://invasive-species.extension.org/can-prescribed-fire-be-used-to-manage-japangrass-stiltgrass-japanese-stiltgrass/

https://www.canr.msu.edu/ipm/Invasive_species/garlic_mustard/management_options