--does tend to be more axonal than demyelinating due to the mechanisms involved, though one can get secondary demyelination if the axon frays.

In general, it's much easier to repair myelin on nerves than the underlying axon, provided whatever is causing damage abates. So axonal repair takes a long time. It's been estimated that under optimal conditions axons can grow at a rate of about a millimeter each day, but that means for long axon branches repair can take months to years, and there will probably be some odd sensations along the way as the fibers have to fight their ways through and around other tissue. Very often such repair is patchy and incomplete, and the nerves regrow in rather different pathways than they originally were.

I would think that with vasculitis if the damage to the blood vessels can be controlled, and the swelling and inflammation reduced, that would give the nerves chances to regenerate. But given the "flare", "relapse-remit" nature of a lot of these conditions, nascent repair might be setback during the next flare, and the process might need to start over again. I'm not surprised that you're reporting a slow spread of symptoms even if their severity over time does not differ that much; that would be expected with a slowly spreading/progressing vasculitic condition. The key would be to get the autoimmune process and attack on tissue as controlled as possible.

I have a friend with Bechet's (one of these conditions) that reports his neuropathy seems to get a little better from time to time, then relapses when he flares, particularly in those areas of the body in which he gets swelling. It's very much a pattern and seems to be related to his fluctuating steroid dosing (that is used to help keep the Bechet's in check).