Bad news: this has bugged users for years. Costas has created an official converter for TheWord; and the guys at MySword have done the same. But there is no tool that converts backwards.
Good news: there are very few modules that exist as TW modules, but not as eSword modules.
Is there something specific you are looking for? Or are you switching from TheWord to eSword?
I download many mysword modules for chinese, and I can't find the source, so I want to convert them to e-sword and theword that I can use them on my PC.