Took me a while but I retried. It's definitely better, to the point that I have to stretch a bit to find really bad errors. "B begat C" still makes it in as do a few similar ones but considering how pathological a case a single-letter identifier is I can forgive that.

I assume because the identifiers aren't unique that they're returned in the underlying api as text locations. Hmm now I want to throw EDGAR data at this.