Despite your frantic hand-waving there were threats not very far away and the Darrians were aware of them.
Bullfeathers. There were no threats. That's why the Itzin Fleet
chose Darrian. They were running away from the "frying pan" of the collapse of the Rule of Man and they weren't going to do so by jumping into the "fire".
The Vilani, hence the Rule of Man, hence the Itzin fleet was well aware of the Zhodani in the Spinward Marches...
Vilani traders encountered the Zhodani circa -2000 IE or ~500 years prior to the Itzin Fleet's operations. Where those encounters took place isn't exactly known, but the "Gvurrdon's Story" in the Vargr AM strongly suggests they took place in the Extents. We also know from canon that the Vilani were barely active in Corridor, even less active in Deneb, and that only a single colony of Vilani separatists existed in the Marches.
Those Vilani traders weren't in Marches because there was no one in the Marches to trade with. They were in the Extents where the markets were. When the Zhodani met those Vilani trader in the Extents, they weren't going to hand the Vilani a map showing them the Consulate's borders. As for the Zhodani being in the Marches, they weren't, they failed to note the Darrians presence in the Marches for several centuries, and they only went looking when the Maghiz indicated something strange had happened.
... and the Vargr in Gvurrdon sector...
The Zhodani knew the Vargr were in Gvurrdon. Whether the Vilani did is unknown.
... well within the reach of jump fleets of the time.
Bullfeathers again. The Zhodani had jump3 and the Vargr wouldn't have it until they stole it. Even if both knew about the Darrians no one is dispatching a battle fleet 20 or 30 parsecs to fight a war without bases and other logistical support.
The Itzin fleet surveyed the Spinward Marches and specifically noted the Zhodani.
The Zhodani weren't
in the Marches. They wouldn't be in the Marches until the Frontier Wars. Look at the maps and read the history in
SMC. The Consulate
patrolled the Marches on a schedule which saw sweeps centuries apart. Once again, centuries passed between the Itzin Fleet's arrival and the Maghiz without the Zhodani even suspecting the jump capable Darrians existed.
With the information in the CT Darrian module neither you nor I or anyone else knows what ships the Darrians made.
We can either make plausible guesses based on their capabilities, industrial capacity, perceived needs, and other factors or we can make crap up because it sounds cool. Take your pick.
I find your pretence of knowledge laughable.
I'm making a plausible guess based on the few facts in canon. You're going with what sounds cool.
With their Solomani tech background the Darrians knew that spinals were the real battle-winning weapon of the time.
Yes, they would have known spinals are win battles and win wars. Whether they believed they needed to build spinals is the question. Whether the Terran Confederation, Ziru Sirka, and Rule of Man ever built rider/tender combination is another question.
With large interstellar powers close by only an idiot would not at least experiment with real weapons.
Sixteen warships is not an
experiment especially when we can make a rough estimate as to how few starships the Darrians had.
The Darrians might very well have built some.
They didn't perceive the need. They could. Whether they would is the question. They also didn't build as many starships as you want to assume.
The Maghiz destroyed
half their starships; military, exploratory, and commercial. The collapse was so far along after 20 years that the Darrian colonies gave up trying to stay in regular contact with each other. What ships there were that still worked were parceled out
three a colony. Depending on how you want to read the maps, that only amounts to only ~40 to ~60 ships being left. Combining that with the earlier 50% losses and deliberately erring on the high side, that puts the
entire Darrian starship inventory at the time of the Maghiz at around
200 ships.
That's two hundred ships out of which you'll need to support explorations within a 20 parsec radius, commercial shipping, government couriers, colony logistics, a navy, and all the other jobs starships are used for.
Which would the Darrians have built more of? Single role warships? Experimental warships? Or multi-role ships which happen to be armed?
What is plausible and what just sounds cool?