Had my follow-up visit to the 2nd procedure today. (To see the discussion of Dr Arata’s new CCSVI treatment center, see the thread about him started by lovebug.)
Keep in mind, this is my version of what he said--I could be off on the medical terms.
Good news:

The improvements I reported above (less a.m. stiffness, better bladder control, less swollen/lighter feet) are still holding.

Dr A doesn’t expect me to restenose again, because he opened my azygous & IJVs really wide—20mm for the right IJV. (He agrees with Dr Tariq in Kuwait that this is the way to go.)

I didn’t have May-Thurner.

We may have found the root of my problem—I don’t have a left ascending lumbar vein as I should; instead, I have a “lacy network” of tiny veins.
Bad news:

There’s no treatment for such tiny veins. So, although ballooning the azygous will help drainage out from the network, nothing can be done about any blockage or reflux inside that lacy network.
I’m still absorbing this news. If it means that I’ll stay how I am forever without getting worse, I can deal with that. Maybe I’ll pursue some of the iron removal ideas in this forum. But I think I’ve gotten all the benefit I’m going to get from liberation (and I’m not sneezing at that!)
I guess I’m more proof that PPMS does not have a simple open-the-neck-veins answer.