Thanks for the above extra information.
It's interesting (to me) that none of these Union officer reports above refer to any of the captured colored men as being armed soldiers/combatants (except perhaps, for the reference to the 'colored rebel scout'). Is it possible in these instances that the reporting was merely describing unarmed 'accompanying persons' - meaning they were cooks, aides, servants, laborers, etc.? (Additionally, it's claimed there are no Confederate references in the ORs to any black rebel soldiers, adding weight to the belief there were no colored Southern combatants).
There appears to be various accounts outside of the ORs in peripheral reports, like newspapers, memoirs and unit histories, of Federal encounters with single (usually) enemy black sharpshooters in the field. For example, in 'Berdan's United States Sharpshooters' by Capt. C. A. Stevens (at pp. 55-56), there is a detailed description of an encounter with a 'Rebel Darky Sharpshooter' during the Yorktown siege in 1862, culminating with the African American marksman being brought down.
It seems from readings, there are several isolated accounts (although not reported in the ORs) by Union soldiers of confrontations with single Black Confederate sharpshooters, which ended with most of these shooters being killed in action.