A DA will probably, It's hard to assess any of your problems without seeing it in person, but people have had success using a DA polisher to get the clear back from the sanding. Subaru clear is super soft and can easily be corrected with a finishing polish and a Flex DA polisher, most of the time, so I would imagine that a DA polisher can correct a sanded clear on these cars.
If I were you I would buy a polishing/compound kit that includes a DA, comes with everything from backing plate to pads to polish to cleansing brush. Always remember that you use the least aggressive method first and if that doesn't work, you move up to something more aggressive.
Also, wet sanding isn't always necessary, you can use your newly bought kit to help get rid of any other scratches/swirls you may not desire, but remember least aggressive first.