...A bit of fan speculation on my part, but i think that there is a chance that koestl might be translating either Aiyoku no Eustia, or Rui wa Tomo wo Yobu. He said on his twitter how he had previously read the game, and liked it a lot (presumabley a rating of 8 and above). So, being a fan of his work, i immediately went to his vndb profile and looked at his votes. There i learned that all his games at/above the rank of 8 were either already translated, old, or weren't "popular". The only exceptions being the two mentioned above, White Album 2- Closing Chapter-, and Natsukumo Yururu. However, in respect to White Album, why would a company want the sequel translated before the first one (opening chapter)? Natsukomu on the other, other hand (my left hand) just doesn't seem like a game that'd be officially translated (basically it's a gut feeling i have). So, that leaves us with the two. I honestly hope that it's the former, but i'll be happy regardless. Remember, this is just me on a whim.
Twitter:https://mobile.twitter.com/koestl
VNDB: http://vndb.org/u25770/votes?c=all;o=d;s=vote