Re: negative balances, I did check an address on prohashing and it shows a zero balance instead of the 2240 negative that a posted address had.  So explorer error is legitimate explanation.  I didn't test, so that's just a single data point.

Re: Code.  I finally started to figure out github commits. I will say this- look at the code, especially in April, and you'll see several attempts by justin to fix the drift.  The thing that sticks out to me is the coding style.  Look at the multiple attempts prior to May 24th.  Then look at May 24th.  Style is totally different, with lots of commenting in the code, and an entirely different fix. 

This is all in addition to the time/date stamps of the commit.  Look at the commit from SHIELD on dated April 5th.  The code is identical to the May 24th commit by justin.  The story that XVG/justin pushed a commit then pulled it off and that XSH copied it is completely implausible.  XVG/justin was still dicking with drift times on April 6th. 

During all of this looking, I had a minor epiphany.  Justin-V-for-Vendetta.   Think he has a vendetta against XSH devs?  Because some devs didn't agree with direction Justin was going, so they left xvg, forked it, improved it, and launched XSH?

Next question:  In response to a recent issue, the reply is that XVG is switching to BTC core.  Where did they get that idea???  It's been publicly announced that XSH is migrating to btc core, so now XVG is, too?  Interesting...

references: 
xvg github timeline:    https://github.com/vergecurrency/VERGE/commits/master
Shield repository:  https://git.shieldx.sh/SHIELD-team/Core-Projects/SHIELD/commit/c9da6eb64f670a6e0336ceb10332b2bd94498eba