Hi /mmd/,
I've been working on a fork of the MikuMikuOnline source code over the past moth to not only translate the UI into English, but to also make it faster, more stable, and eventually adding more features. I have finished the first full release of the client which includes a new title screen, loading bars, English UI, and a redesigned chat UI.
If you want to test, you can find the source and releases here:
https://github.com/figamin/MikuMikuOnline_wss-modNote that you will need Visual Studio 2010 in order to compile the game. I have included all the needed libraries in the repo.