Interesting theory - but personally, I think that if Windrunners could create a storm (I’m saying ‘could’ simply because I use that for everything that’s not directly stated in a book or confirmed by WoB), it wouldn’t be a highstorm. I say this because that would require the Windrunners to produce a new source of investiture on Roshar. Move the existing highstorm around? Maybe. Make a new source of investiture with existing investiture? I’m a bit skeptical. I think that if this theory is true, then the reason that the Stormform Listeners could summon the everstorm is because it’s Odium’s version of the highstorm - his manifestation of investiture on Roshar, in contrast to the highstorm being Honor’s, meaning that it’s summoning/creation couldn’t be replicated, but the Stormform Listeners could probably make normal storms, as could the Windrunners, their presumed KR counterparts.