In the light of this http://www.creationkit.com/Talk:Bethesda_Tutorial_Optimization#Graphical_Anomalies, a project for a scripter (maybe me down the track)- and perhaps for the excellent TES5Edit collection- is to cycle through all room markers in a cell and search for the interfacing edges. Given some input tolerance, a page of data is presented to the user who is prompted to enable the script to autocorrect or adjust any under/overlaps in room marker fit.