I completed testing and filed a bug report.

Summary: Testing indicates that chirp import routine for this radio doesn't handle either empty fields or "spaces" in fields that are otherwise properly csv-delimited. Until this is changed, we must FILL referenced fields, even when not used, and CLEAR otherwise empty fields, such as Duplex. It's the work of a few minutes to do this. Otherwise, Excel files seem to work when exported to csv and imported into chirp, so there is no format flaw introduced by Excel, such as the wrong number of trailing commas, etc., at least in my testing and use.

73 Rich NE1EE