Given the small reveals of future characters that are not in the next immediate arc, I'm pretty sure that was a "buy our novel to get the rest of the story!" like most LN adaptations... :\
@welcom2atlantis well to be fair she wasn't a subordinate she was a tool what with the curse that not only sapped her free will but also instigated her into trying to kill Cordelia also pretty sure they were planning on killing her either with the curse or something else after her mission
that the status is cancelled means they planned to continue but found it wasn't popular enough or selling well enough to justify it and cut it off. in all likelihood they had no choice but to hint at future characters so as to try and make people want to continue following the story.
such a shame because seeing the manga after reading the novel would have been fun and refreshing