It remained very obscure, so I didn't get much reaction from the community writ large. However, one Vocaloid fan did find it, about 6 months after its initial publishing. Their response - and no, this is not a joke - was to congratulate me on my impressively deep knowledge of the Vocaloids because I knew of obscure characters.
A bit of asking later, I gathered this is because of a single line that offhandedly referenced Calne Ca, a Vocaloid who looks like Hatsune Miku mixed with a giant spider. I just happened to stumble across her while doing my hour of online searches, and having already decided on the dragon woman as the main antagonist but thinking that Miku but a spider sounded metal and I wanted that, I just threw in a reference that the dragon was sent by Calne Ca. This doubled as potential sequel fodder, so I could go through other characters sent by Calne Ca as Miku learns about more and different subtypes of metal with her new friend, perhaps culminating in a fight against Calne Ca herself. Those sequels never materialized, though I have considered going back just for fun, or rewriting it to be original characters only. Whatever the case, the irony of someone finding my knowledge of the characters to be particularly extensive was not lost on me.
I do remember my DeviantArt username! In fact, with knowing it I just found the story inside a few seconds. I'm... nervous to put a link to it, since that would enable looking at other parts of my DeviantArt account and I don't want that to happen. If you are super interested, let me know and I will DM you a file (not that that makes it especially hard to find the original document by doing a text search but it makes me feel better XD).