TrulyTragic

personally, i feel the sleepless were suppose to thematically mirroring the Adonalsium shattering event as a world-building element, not as a foreshadow for a plot point, even for later stage. otherwise i found no major draw back nor error in your theory, neat work, it seem legit enough as far as head cannon goes though it didn't convinced me. (and i think the linking of hoid/kelsier conflict to sleepless/hoid is a bit stretching it)

i have a feeling that whatever the Shard-shielding technology those Ire people have, they stole/figure out that from Hoid, or at least interaction with Hoid made them realize it's possible, he's still the only character that can do this consistently that we know of.

I agree that with the way it work up to Era 2, an F-iron kandra wouldn't be able to store the weight of their bones at all, stormlight healing or F-gold do not restore your favorite jacket to it undamaged stage after all - that's what bones are to kandras. However, with information hinted at in RoW and Sixth of Dusk sequel reading, i believe the there will be ways to forge a Connection to an entire space/vehicle then use the available investiture art with it in space era, so we won't see any set of weightless bones till then, if it even worth doing that tbh.