If you look in the Format Attributes section of the reader, there are a lot of kml attributes that can be exposed, including kml_name which may be the one you are looking for.
That Unexpected Input warning normally points to an issue with the Reader, not the writer. It is saying that the file you are reading in has 9 features that could be read but were not because they are in the feature types StyleMap and Style, not Placemarks. If you wanted to get those features you could try updating the reader and its feature types to include those or try adding a new kml reader that is Single Merged Feature Type instead of Individual Feature Types. If you were expecting placemark features, then there could be another issue.