Whoa whoa whoa, why wouldn't our stuff count as 'technology', Dark Tapestry origins or not? Literally all products of dath ilan are made from 100% natural atoms! There shouldn't be anything extra or weird about repairing a dath ilan object compared to repairing any other object.
Greater Make Whole doesn't specify that it fails on unique creations like paintings, so it has to be reading from the object's past state rather than comparing to an idealized extrapolated blueprint or to similar intact items elsewhere.
Repairing Merrin's armor should just work. There's no reason to get Greater Reality involved in this.