What is TCX?
TCX is Garmin's training format: a GPS track with heart rate, cadence and lap structure wrapped around it. FileSorcery reads it and converts out. Writing one is deliberately not offered, because a schema-valid TCX needs activity timestamps that a converted file cannot honestly invent.
What is KMZ?
KMZ is simply a zipped KML, and it is what Google Earth actually exports - the zip lets one file carry its images and icons alongside the geometry. The geometry converts; the artwork inside does not, and the result says how many pieces were left behind.