Sorry for the long delay, unfortunately I am not able to track forum due to mailing issues. So I might miss some posts here. GitHub issues tracker
is much more reliable and convenient right now.
Anyway, on the question:
So far non-editable fields indeed aren't visually distinguishable, but you can provide some leading or trailing component or simply use an overlay which will be displayed when field is not enabled/editable. It is an additional code, yes, but it should do the trick.
Later on I will certainly improve field visuals to add feedback for the case it isn't editable.