That wouldn't make sense though, as he'd be stuck in his whole blind/deaf state until someone touched him?
But when I meant lending out his soul too much (and it's my bad for not being clear enough), I meant that since so many people had fragments, he wouldn't be possible to kill conventionally because there's still some piece out there to reform him eventually. Bad example incoming, but kinda like Cell from DBZ, you have to kill and vaporize all of him to truly kill it, otherwise he can reform from a given fragment. So even if Bach was killed off, some bit of his soul out there was gifted to another, so he just took a thousand years to reform back slowly since he couldn't lend out as much. At least that's what I got from reading it and theorizing. So like you said, kind of a limbo state.
But who knows, hopefully we'll get a bit more history. Makes you wonder if he's even truly a Quincy since his powers are so dissimilar in a way.