Yep, as a Python dev that's used to Python looking a certain way, this is very offputting. This is a great project, and I would hate for it to look "off" by something as trivial as Javascriptish whitespace and formatting conventions.
You're encouraged to follow PEP8 completely for your Transcrypt apps and libs. As for interop with JS libs, following JS conventions is probably best, although some often use libs may acquire a PEP8 facade.
There are spaces before subscript operators, before `.method()` calls, and between `def name` and `(param1, param2)`.