The Europe Fan Fest was in English because it was being held in Europe. They couldn't very well have the thing in Japanese while it's being held in Europe.

But since Tokyo Fan Fest is being held in Tokyo, there's really no need for them to have English for anything but the keynote. The attendees are going to be 99% Japanese, with maybe a small number of foreigners. So it really doesn't make sense to translate the side panels.

Later, when the side panels are available online, I'm sure some FF fan will translate them (and I think they often post summary translations here on the forums). I've done a bit of translating as well, if I have the time.