So, I think there are pretty good arguments for either approach to getting the Scylvendi into position to attack the GO. As far as going around the Neleost, there would be several disadvantages, the way I see it. One: time. The GO is busting ass to get to Golgotterath before winter sets in. If the Scylvendi are meant to attack them soonish, I'm not sure they could get around before deep winter hits. They would probably be delayed until spring, which would probably be too late for Golgotterath if they were needed as reinforcements. Two: at some point, they will encounter the denuded land that both the Horde and the GO trampled over and decimated. They would have no food or forage, and wouldn't necessarily have a Horde of sranc to eat to sustain them. Additionally, they would probably run into that situation as winter is setting in, making forage even more difficult.
On the other hand, Cnaiur was one of the principals in the Holy War that supervised the crossing of the entire army across the Sempis, arguably one of the greatest rivers in the Three Seas. I also don't think there's a bridge over The Leash, but surely he, of all Scylvendi, could orchestrate such a crossing with great rafts, barges, ferries, something of the like. He didn't seem to have any compunctions about crossing water, as he did it many times on scouting raids and such, before the Holy War actually crossed. I imagine the Consult would employ Quya to keep the things steady and/or to propel them across the water. Similar to Kellhus' Raft, but arguably easier since these would be floating on water, and not in the air.
I think my two cents were spent long ago.
You make some really good points. Lack of forage and winter setting in would be a huge problem. On the other hand, and maybe the scale of the map is off, but as I look at it, it seems the leash is wide enough that you couldn't see across it, and that seems like a tall order for rafts packed with horses and men. They'd be fighting the tide too. Perhaps it narrows considerably in places, and in that case, I am sure they can figure something out.
I just can't imagine there is a bridge. Kuniuri was a bronze age society, and 2000 years have passed. Does the Consult have a workforce skilled enough to build a bridge that long? It seems unlikely.
If the Consult had some means of conveying the entire Scylvendi horde across the Leash, I feel like we would have seen it by now (of course we had no inkling of the nuke). And I can't imagine the nonmen ferrying them across in some way.
Improbable, yes, but not impossible. Access to soggomant would kind of allow them to make anything damn near indestructible. Did they bother to though? Probably not.
They have access to it, but not an unlimited supply. It's not a metal that originated on Earwa, and they'd be unlikely to strip away so much that it weakened the Arc.
Hmm, this has me wondering, the Quya that the Consult employed, were they from Golgotterath or Ishterebinth? Because if they were from the latter, they might all be dead now...
My assumption was both.