I think it's fairly important to frame answers to this question in the context of typical advice - because this is a rare situation where typical advice may not make sense (which makes this question not a duplicate of the many well answered questions about how to list job titles on resumes.)
Resumes are sales tools. You are selling yourself to potential employers. So, you should try to follow typical best practices for other sales tools: You want your resume to be interesting, relevant, and truthful.
When it comes to listing job titles, people sometimes have the desire to lean heavily on the interesting and relevant criteria, and come up with great-sounding or "more standard" titles than they actually have. This is often advised against, because it can be a slippery slope. Providing titles that have any chance of being interpreted as misleading (when compared to your real title) can leave you looking like you're trying too hard, or that you're downright deceptive. Those are not the traits you want your potential new employer to identify you with. Hence, typical advice is to be 100% literal and truthful with your job title on your resume, and then use the description you provide to actually lay out what you really did. This is a best of both worlds approach because it allows you to remain honest, yet still provide relevant detail.
However, in the case of a (deliberately?) obscure and unintelligible title, it's arguably not the best idea to follow this typical advice. If I was hiring for a back end developer and I was scanning through my employer's HR recruiting tool (which pulls job titles from your resume and lists them next to candidate's names in a list) and I saw QCV Editor, I would be confused, at best - or turned off from looking at you, at worst.
So, in this case, as suggested by other answers, it probably makes sense to list something else - perhaps with an explanation of the internal title. Such as,
Back End Developer (QCV Editor)
This will help avoid confusion while still allowing you to (more or less) remain faithful to typical advice about not "faking" job titles.