I don't know if he can help with your specific repair, but there's a shop owner named Aoyama-san who comes highly recommended by me and a lot of other members. His English is very good and he specializes in custom-fitting bikes and equipment. He used to work at Y's in Akasaka, but now has his own shop, HiRoad, a short distance from Gotanda.
Cherubim frame builder is near my house, but I have never ventured into his shop! I think he exhibits at USA shows, so there is a good chance he speaks English. Here is the link: http://www.cs-cherubim.com/ He is a supreme frame designer & builder, and I think it's worth contacting him to see if he can help.
You know, one of these days I ought to go into that shop!
Other than that, I think quite a lot of bike shops have relationships with frame builders, so maybe they could act as an intermediary? - assuming someone in the bike shop can speak English!