"By clicking on the image, an interactive demonstration of the Tcl/Tk application is launched using CloudTk."

No it isn't; I just get an empty frame with a close button. This is consistent on multiple browsers/platforms.

I'm guessing it works fine until there is load :). The design does seem to just proxy noVNC to a Linux host.

I wonder if you could maybe just compile wish to Wasm with Emscripten?

Worked for me

same here