I empathize with your ambiguous results, although I've had enough positive signs in my own methylation ramp to feel hopeful.
It's appeared to me that as I've gradually increased my daily dosages, that I end up with sleep troubles for several days, and then I adapt. When I've jumped the gun too much, then I ended up with more extreme symptoms -- feeling really "overrevved" for several days, eventually becoming "wired and tired". I never stuck that out that state long enough to see where it headed; instead, I pared back my B12 to a lower level and eased my way up. And my body does seem to adapt to that.
In addition to easing up dosages, I've seen similar effects in changing B12 toward more relevant forms. I started with the hydroxyl-B12 drops from Holistic Health; I had insomnia problems with this, and felt a little "overrevved", but adapted. After making it to 1mg of that, I switched to Jarrow methyl-B12 and again had startup symptoms, but made it up to 1.5mg (plus still taking 500mcg of the hydroxyl drops and 500ug adenosyl-B12) and adapted. I recently discovered a thread here on PR about Jarrow not being as effective for people anymore, so I've gradually replaced it with Enzymatic Therapy; and I seem to be experiencing similar startup symptoms again, as I've increased the portion coming from ET. I've recently reached the point of fully replacing Jarrow with ET... we'll see if I get my sleep back in the next week, as I expect/hope to.
When I have the sleep issues, I hit it every other night with some Lunesta, to ensure I get some sleep. As I think others have found, I've found that bad sleep exacerbates my fatigue/muscular symptoms, and Lunesta seems to give me good enough sleep to counter that.
I don't know if this approach will hold true for everyone, but it seems to have worked for some others as well.
Per your comment about adenosyl-B12..... Adenosyl-B12 may not help much with methylation, only with the body's other B12 function, which involves some forms of energy production (BCAA breakdown, beta-oxidation, and any other pathway producing proprionyl-CoA/methylmalonyl-CoA). The body may have a way to convert adenosyl-B12 to methyl -- not sure -- but it seems to me much more likely it'll get used up in the other function, since doing so requires no conversion and there's likely a need for it there as well.
So the point being, if the negative symptoms you're experiencing are from methylation startup, then it makes sense that adenosyl-B12 doesn't cause those same symptoms. But if you switch completely over to adenosyl, then you may not be increasing your methylation much. I personally think all three forms have their uses: higher doses of methyl to directly help with methylation, some adenosyl for energy production, and hydroxyl lets the body choose where to put it, provided it's capable of converting it. I'm currently using 1.5mg, 500mcg, and 500mcg, respectively.