I did the same on the highest bolt on the passenger side. Even with an socket extension, the ratchet drives the bolt at a slight angle because of a crossmember preventing the tool from being held straight and makes it easy to go in cross threaded. I couldn't draw the bolt in all the way and being afraid the snap the head off, I left it like that. This attempt at installing it was done without lifting the car whatsoever but I was able to shimmy under the car to do it. FWIW, I had no problem doing the same mod on my 2011 Outback 5 years ago but it definitely has more clearance to get under there.
For my second attempt to install/correct the issue, I took the car to my parents place where I have my floor jack and stands and most of the quality tools including my tap & die set. I raised the car and ran an M8 1.25 thread tap thru the hole. It started smooth, hit a little resistance and then went in smooth the rest of the way. Once that was done, the bolt went into the correct thread and tighten up without a problem.