Some of it is interesting; though I can see some minor issues;
Firstly, Colleton's fate isn't particularly plausible, there aren't that many lieutenant-colonels in any military service, and when they find no LTC Coleton in Confederate records, somebody is going to do some digging.
That, assuming that Colleton doesn't have an identity card or dog tags or something.
I'm somewhat doubtful the US would ever try Lavochkin or Martin or anyone in connection to Hardeeville. What side prosecutes their own soldiers? And even if they did, the public outcry against the trial would probably be enormous.
I find it somewhat doubtful that unlike OTL Neo-Nazi organizations, Order of the Blue X wouldn't be especially vengeful about targeting blacks. It'd be as if Neo-Nazis didn't target Jews (and even when they don't, it's usually because Muslims have become their new favorite target, and for the nonce, they're too busy heaping praise on Israel).
But other than that, I rather like these vignettes!