Hard to say which drives support C2 reporting with so many drive models out now.
The reliability of C2 reporting, however, is ~100%. If a drive says it had a C2 at a given point…then it did. This does not mean that another drive will have a C2 error at the same location. Remember…C1, C2, CU are all drive dependent and not media dependent. It all depends on the drive that is reading the disc at the moment (some drives can read scratched discs while others can not). A ‘normal’ C2 does not actually exists on the media itself. It is just the drives ability to read the disc at a certain point. But, a C2 can be deliberately mastered onto the disc. This C2 can be read back as a C2 or maybe worse, depending on the drive.