Only one question arises that pushes me back: does anyone else think doing a beta could make us settle with it and leave the project without completing it?
I know that I'm not helping on this project, but I've discussed things with BeautifulBeast off of the board before.
My opinion is that doing a release now has a high probability of causing the project to stagnate.
I've been in a similar situation before. In my case, we were excited to make a release and once we did, it took 5 and a half years to re-start the project.
The JUSTP already has more going for it than my project did. I'm actually amazed by the progress that's been made.
So, here's the other side that's also very realistic. If you do not do a release until it's done, the project still has a good chance of stalling (since it seems that it's already going down that path). So, if you wait until it's 100% and it becomes stagnant, nobody gets to use it in ever.
I think it comes down to how playable you think a current-state release would be. If it's well done and makes the game playable to a new audience then it will probablly cause the project to gain more attention which could help further the progress. Also, if a release will help people play the game that otherwise wouldn't, then you can feel good about it.
Just be prepared for the negative comments. If it's not 100%, there will be people that don't understand the effort that you've put in and just think you released some half-baked garbage even though they use it and it's better to them than a fully-Japanese version.