50mg of methylfolate; that's an insane amount! How did you decide/determine you needed it to be that high? What symptoms responded to it so you kept pushing it up that high?
Sorry for the delay in responding...sometimes my alerts don't work properly.
My primary symptom in judging need for methylfolate is chronic runny nose. Other primary symptoms are angular chelitis and increased gastric issues (mostly looser bowels, sorry for TMI). Simultaneous runny nose accompanied by sudden onset angular cheilitis (it can appear within an hour) means an automatic 10-20mg dose on the spot.

The angular cheilitis can disappear with just a few hours. So basically, epithelial symptoms are what I use to determin the need for more methylfolate. Other symptoms can include mood issues, wired-ness, fatigue, etc. I also got some potassium deficiency symptoms in the beginning, although those are long gone. But the epithelial symptoms have been the most sensitive barometer. I get epithelial symptoms before the more annoying and troublesome symptoms manifest now, although when first starting methylfolate before I got to the high, stable level, all the symptoms fluctuated a lot. Seemed like I had to get "topped up" with methylfolate to get to the deeper healing. Epithelial symptoms will still appear if I get too low in either methylfolate or mB12, so I'm conjecturing that they're indicative of really deep, long-standing problems that are being worked on. Can't prove it, but that's what I think.
I stopped upping the methylfolate when symptoms stabilized and didn't return. Periodically I would try stepping down my dose but symptoms would return. When I could successfuly step down my dose from the all-time high, I would leave it at the lesser levels for a while then try to step down again, always adjusting for symptoms.
The only symptom that has never really resolved is the gastric stuff. But it got much better after a while on high-dose methylfolate. Gut therapy helped it some more. Now B2 + Mn seem to be helping still more (with firmness/consistency and "color"indicating better digestion, again sorry for TMI). I'm not entirely normal with gastric yet but not sure I can get that way given some other things currently going on with me. It's been a big damn process, for sure.
Edited to add: I didn't make clear that I didn't stay at 50mg for very long. My months-long high dose was 40mg, though. I hit 40mg, got fairly stable (within the caveat that at least the first 3/4 of a year of methylation protocol weren't very comfortable in general, just a lot of physiological changes and tweaking of this and that for various symptom manifestation), then tried 50mg to see if the extra would help me stabilize further. It didn't, so I went back down to 40mg/day after a short time at 50mg, then stayed at 40mg for months.