Is the state of Ihram considered valid, along with the subsequent dissolution thereof, if one is afflicted by impurity during circumambulation, given the doubt as to whether it reached certainty, and does this necessitate making up anything?

If you are certain that there is impurity on the ihram (definition), then if you became aware of it after the tawaf (definition), the tawaf is valid. If you became aware of it during the tawaf and completed it, there is a difference of opinion. The stronger opinion is that there is no harm in the tawaf, but a sheep should be sacrificed and distributed among the poor of Mecca. As for the presence of impurity on a child during tawaf, it does not affect the validity of the tawaf if the impurity does not reach your clothes.