As a follow-up from the post above
From what I recall, there was a poll for the most liked character which was Miu.
So Insem decided to translate her last since people would otherwise -possibly- only read her route and move on if he released her route first as a partial patch.
The rest is in the post above.
Been a while since that poll so correct me if I'm wrong.
Post: http://staircasesubs.com/2012/07/02/common-route-complete/
Edit: Added link to the post in question.