I had those speakers for a few years before someone else noticed it, lol. The other tweeter worked just fine, and the speakers as a whole were so good that even without the dedicated hardware for higher frequencies it was still better in those ranges than what I'd been using.

I don't know how likely it'd be for something like that to turn out unsalvageable. I think that essentially everything at that level uses wooden enclosures, so it'd come down to whether the speaker bit is set into the wooden enclosure with screws or adhesive, and I don't know about the industry enough to know what the ratio is on that. Probably mostly screws. Then getting a compatible driver is probably guaranteed, at worst you have to replace both sides to keep them balanced.

Lots of defects in speakers are actually serviceable for a reasonable cost. For high-end speakers, I think it is worth trying.