Well, it's been over a month. I came up with a more permanent solution. I took out the paper, it didn't really help much with friction; what had actually fixed the lurching issue was adjusting the front brake activation screw so that the sensor for the brake light (and regen) was/is activated/released after the screw contacts the brake rod/piston. Anyway, my solution was to put a small piece of metal in the spring slot (which is way too long for the spring) so that it would actually have decent compression/recoil strength. In addition: My new handlebar setup worked out so that it was convenient to have the bottom of the brake lever rest on the front right turn signal; any bump/wind energy will have to overcome the friction between the lever and signal before the lever can move.
While the lurching (of all severity) has completely vanished, there are still a few troubling lingering symptoms; which suggests that there was either a secondary issue or that the regen somehow caused damage to the motor or some other part. The bike now makes cackling/crackling/grumbling/popping sounds, sometimes followed/accompanied by a lack of power. I've heard my bike (or other Zero's) make sounds similar to the least concerning sounds (low cackling/grumbling) among this new sound regimen; but as far as I remember they were rare, short, and not followed by any performance issues. It happens most commonly when the bike is asked to work hard (go uphill from a stop or in high torque setting). Here are the instances I remembered to make note of (sorry I wasn't more detailed, I'm usually going to work when it happens): 1. Motor didn't respond to throttle after switching to sport. (I think I had to switch back to eco). 2. While in sport (probably stopped at a light), I fully opened the throttle and was rewarded with a concerning lack of response and a nasty sound. (I think closing the throttle and re-opening worked that time, I might have done it a few times very quickly). 3. On Oct 30th; Shortly after leaving the house (or, if I failed to notice it, perhaps as soon as the bike had booted up) the warning light was flashing and the power output was uneasy (I think it was also making some sound), I rode it like that for a little over half a mile hoping for some hint as to what was happening (and waiting for a safe spot to pull over). The bike worked fine after restarting. 4. A few days later crackling and 1 pop from ? the motor?
The sound and power issues are relatively sparse, but occur in clusters; I'll have several trips with no sign of any issue, and then... there will be a trip (or two) in which I hear the various sounds anywhere from twice to ~ten times (the sound is less often accompanied by a noticeable performance drop).