I suppect some buoys "names" aren't names but part of light characteristics:

seamark:light:group
seamark:light:height
seamark:light:period
seamark:light:range
seamark:light:reference
seamark:light:sequence
seamark:name

I know you didn't change those names, but it would make sense.
The raw information (extractible with GDAL) can be found on ENCs AR201010 and UY200001