I'd go with a comic book series title shown most commonly on the book covers. The Indicia show the legal title of a series. But the popular title used by the readers and fans would be more accurate in referring to a series, as the legal definition often deviates from what was actually on the books, and completely unrelated series titles can differ from the series in question by something so small as using a dash between a two-word title. In such cases, in which the two unrelated series would otherwise be indistinguishable, they would be confused, and taken for each other. That possibility is why I would always use what is most commonly written on the issues covers rather than the indicia (as that is what most readers and fans know as the series title).
And yes, GCD always has many uncorrected errors remaining on its database at any given time, and so, cannot be trusted as the ultimate authority in every case.