Spotlight rotation values do exist to some degree upon import, but are extremely scuffed. It's likely the original data was not properly parsed into Blender as this effects the scene there too. However, the rotation values present may be able re-parsable, (as in, values reorganized, flipped, multiplied, whatever) in Unity to provide more accurate results.
Over time while tackling this issue I've made some debugging tools which may be of use to anyone else who wishes to embark on this subject, I won't include those in any released, but will be provided in the repo
Spotlight rotation values do exist to some degree upon import, but are extremely scuffed. It's likely the original data was not properly parsed into Blender as this effects the scene there too. However, the rotation values present may be able re-parsable, (as in, values reorganized, flipped, multiplied, whatever) in Unity to provide more accurate results.