A few general comments as someone who really tries to make every bit of canon material count. Many times writers overlook bits and pieces they just don't remember or are too insignificant to weave together not cause they are bad people, they just forget. I am sure it is just an oversight due to human error.
That being said the 'Federated Suns 237th Light Cavalry Regiment' reference you make I am familiar with. My solution here would be to call them an ad hoc unit assembled for the express purpose of raiding the Taurian Concordat during the war. Perhaps staffed with folks who didn't want any part of the SLDF which I can see and perhaps the AFFS didn't want them either. As I recall my history the Federated Suns is just coming out of a Civil War, right? Perhaps these are Mechwarriors whose loyalty is in doubt. From their unit name it sounds like they are a lightweight unit so they'd be ideal as raiders.
Canonically, the Davion Civil War ended in 2540, more than a generation before the RW started; even if a trooper was freshly-enlisted into the Varnay forces just before they were driven into exile in the CapCon, he’d have been nearing retirement age by the time of the Reunification War. Checking
HB:HD, Roger Varnay tried to return from exile in the CapCon in 2565, but he was intercepted: his naval forces (and their CC ‘volunteer advisors’) were smashed over Kigamboni, and his ground forces (including partisans within the FS itself) were wiped out ‘nearly to a man’ on Wappingers. The few to escape the massacre spent the rest of their days hiding and fleeing from Prince Alexander’s security forces, and Roger himself fled back to the CC and complete irrelevance, so our hypothetical trooper’s
son (if taken during the battle of Wappingers) would be pushing forty by the time of the Sterope debacle. And Alexander Davion explicitly used the formation of the SLDF to dump a large proportion of the AFFS’ accumulated incompetents, no-hopers and ‘attitude’ problems into olive-drab uniforms, which almost certainly would have included anyone still waving the Varnay banner.
Don’t get me wrong: for the purposes of my work(s), I’m leaning towards assuming they
were Varnayist holdouts. Indeed, my working theory is that they’re the composite remains of
three regiments captured and amalgamated after Wappingers for the AFFS to use as a ‘suicide squad’ of sorts, diehards who never gave up hope of escaping or continuing their fight... even if twenty-three years is still a
long-ass time to wait to make their prison-break! (Either that or they were ex-AFFS troops recruited into privately-sponsored mercenary formations, perhaps ‘household’ formations loyal to the new Duke of New Syrtis — whoever
that was in 2587, since Cassandra Davion-Varnay was long dead — that then got amalgamated back into the AFFS as ‘contractors’ or ‘reinforcements’.) I was just hoping we might find some more canonical data, is all.
The second issue seems to be the importance of Sterope which too me is the easiest to explain. Regardless of what status it held as an outpost or new colony the Taurians really put up a fight. I mean if you are fighting over asteroids in space it seems likely they'd contest a planet of minor importance that falls with in their borders. Marking their defenses up as tough seems to be accurate. Enter our ad hoc raiders I described above and perhaps they aren't as focused on their enemy as they should be. Thinking about their shabby treatment at home and would it take that much resistance to really make them say 'screw this'!
Perhaps true... but still, even a regiment of, say,
Swordsmans and
Wolverines is still a
regiment, and to suffer 70% losses against what sounds like militia and fixed defences... God, were they all
asleep when the Taurians showed up? Did they manage to crash their DropShips into each other or something? Did someone get lucky with a nuke or two?
Third their survival into the 31st century is a lot more complex but I am going to chalk it up to lucky banditry. Certainly the SLDF would have wiped them out along the way if they knew their homeworld so I am guessing they never did. Picking their targets well they could have outlasted the Star League and even gotten aid from Amaris (Periphery BattleMech Divisions). From their on out the Succession Wars is a fertile ground for their survival. And the depths that the AFFC had to go to in 3042 to eliminate them indicated they had learned well from their ancient Taurian adversaries.
I doubt Amaris would have bothered with Tortuga — too small and unpredictable to be worth bothering with — but in my set-up they have outside assistance from a non-canon state, even to the point of outright donations of massive infrastructure projects and literally
millions of slaves. Not to mention that it’s also been established in-story that many military-production corporations in the IS simply bribe many pirate-groups to leave their assets alone by ‘misplacing’ a company or so of BugMechs their way every few years, since it’s far cheaper than having to wrangle with insurance companies after raiding shenanigans.
And I wouldn’t put too much weight on the outcome of the 3042 operation by the 9th RCT. That unit was newly-formed and sent to Tortuga for some ‘live-fire training’. They were half-trained, under-coordinated and just plain
sloppy, and they
still cleared the place out, even if it cost them most of a regiment doing it.
