Pretty sure the only long term (3000 yrs) weave of tainted Saidin was the original ward around Callandor that protected it from any hand but that of the Dragon Reborn. And that was interwoven with Saidar, which may or may not have had an ameliorating effect on any potential taint damage to the weave itself. I'd say too little evidence to go on. As far as the corruption of the ways, I don't think it's ever explicitly stated, as no one has been able to make effective study of the ways since they went dark, (the one Ogier that tried had her brain eaten by Machin Shin IIRC), so we're just assuming it's the taint that did it. If it is the taint, then it'll be like madness and must be actively healed. There is the possibility that, like any living thing, the ways got a parasite IE the black wind, and that caused the corruption, growing from some small contaminant and darkening the ways until it became noticeable as the black wind. Thinking about it, in either case, it would likely require a very skilled weaving of some kind (possibly a healing if the ways are alive) to remove the corruption. Probably not a priority. Maybe after Tarmon Gaidon good ol' Damer Flinn will need a new project.