Got a 2012 FB25A. Replaced it with a 2016 FB 25. Put 5 miles on it today. I’ll do a YouTube to show the details, however, the important thing is, if you get a complete motor from a 2016 Forester, it will run appropriately in a 2012 Forester and fit just like the original.
Nothing about the swap was hard. Those oil burners can be replace without spending $4000-$8000. I’m ~$1200 into this one.