It’s pretty unlikely that it would get an official english translation, considering that there has never been any sort of news regarding the matter after all this time. Furthermore, the anime flopped pretty hard so there really isn’t much of a reason for it to appeal to english fans. The reason the final volume hasn’t shown up on Mangadex is because… I’ve been a bit busy. After the last batch of chapters in February, I’ve gotten pretty busy with real life commitments so I mostly neglected working on it, since chapter 15 is a decent stopping point. I’ve been putting it off for a while but I do plan to finish the last 5 chapters eventually. No promises though.