Thom,
Just as important here is the "timeflowPointParameters.type", which I'm guessing is at the default value of "TimeflowPointSemantic", based on the two "location" options of LATEST_POINT and LATEST_SNAPSHOT?
LATEST_POINT is the most recent point-in-time within the timeflow, so the refresh will start at the most recent snapshot for the source, then roll-forward to the most recent point-in-time using Oracle redo log files.
LATEST_SNAPSHOT is the most recent snapshot for the source, so the refresh will end at the time of the snapshot.
If you change "type" to one of the other available values (visible when you use the TAB key), such as "TimeflowPointBookmark", "TimeflowPointBookmarkTag", "TimeflowPointLocation", "TimeflowPointSnapshot", or "TimeflowPointTimestamp", then you'll see the other fields within that data structure change.
Hope this helps?