What are these "nonstandard format" lines in Distant Artificial Satellites Observation circulars?
Those are data from "roving observers", essentially any ground-based observation that isn't from an observatory blessed with a three character observatory code. The observatory code is columns 78 to 80 of the entries. Note that the observatory code for those roving observer entries is always 247".

The longitude, latitude, and elevation of the known observatories are known. This isn't the case with those "roving observers", which is why they take two lines. The first line of a "roving observer" entry contains a "V" in column 15 and "247" as the observatory code. The second line of a "roving observer" entry contains a "v" in column 15. The bulk of the second line contains the longitude, latitude, and altitude of the observer.