Steve,
Klaus is the real guru on this.? See his many posts of years past.
For XML, I use the free "XML Copy Editor".? It's not on the JMRI list but has indentations, colors, etc.
Rember, slow and steady wins the race.? Maybe try just a function key label change, say? <sound-event name="BELL" label="Bell" buttontype="TOGGLE">
to?<sound-event name="BELL" label="Ding-Dong" buttontype="TOGGLE">.? Or, whatever rings your bell:).
Conrad