Don't be intimidated by "methylation". Seriously, all it is is just b12 and the proper form of folate (methylfolate). All you have to do is supplement something like 200-400mcg of methylfolate per day (metafolin), and you can use hydroxycobalamin or methylcobalamin b12 sublingual tablets too. I would stay at 1000 or 2000mcg of b12 per day.
I have really noticed my brain fog coming down and my anhedonia going away. I definitely can experience pleasure a bit more. I still have a looooong ways to go though.