Samigo never sends result of a manually graded Test to xAPI Provider.
Samigo uses the same method call for both auto-graded and manually graded assessments:
There are a few Listeners where this additional code could be implemented for scoring for the events sam.total.score.update and sam.student.score.update.
I personally think this should be cleaned up so that this additional call isn't made and it's all done through the events api. There's currently 2 calls made just on a submission. But even these calls aren't very clear and probably could have a scoring event associated with them along with a submission event (since it will be auto scored)