It says that Browservice runs Chromium.
How could that work for AROS?
Because the browserservice itself is not running on AROS but on a Linux or Windows machine.
The AROS browser uses the proxy that runs on such a machine and the proxy itself directs the requests to the chromium (CEF) instance (that runs in the background on the same machine as the proxy).
CEF renders it's own instance to an image, which is transferred to to the AROS webbrowser. That is what you get to see in the AROS webbrowser. I presume that is why the javascript is needed, in order to transfer the input from the AROS browser back to CEF, so that you can enter url's, click links, fill in edit-fields etc.
That input allows you to "control" the CEF instance "remotely".
In theory that should work perfectly although I guess not so for heavy animated websites (video's), but afaik that is not the aim of the project (even though it does state it works with those as well as long as your connection is fast enough).
If you would have to make a comparison then you could probably compare it with VNC, but with some serious twists.