Based on my experience, CASA ATOs only ask about things you got wrong on your theory exams. It is written on your KDR.
However, FAA Inspectors and DPEs ask everything. They don't care about KDR (your deficiency is also written on FAA written test result form). They will ask everything they want to ask and demand answers.
FAA Inspectors are much harder hardcores compared to DPEs.
But if you pass FAA Inspectors' oral tests, you are pretty good.
