This would be great! In big session it's not always easy to remember which tracks are frozen. I use the workaround to write it in the track notes section, but it is a little distracting sometimes.
Also there is a chance that there are new plugins added to an already transformed track, but then the track can't be transformed back without losing the newly added plugins. So it would be great to have a feature where it clearly indicates that a track is transformed/frozen and maybe the option to not let new insets being added, like for example in Ableton Live, Logic and I think Pro Tools.