It will work, but just bear in mind that you can control what the rotation ‘around’ the Normal Z axis will be (you need two vectors to force orthogonality). Most of the time though that’s not a concern, especially if you’re just spawning FX or something.
If you want to skip having to include the Kismet Math Library, you can just do this:
FRotator MyRotator = FRotationMatrix::MakeFromZ(ImpactNormal).Rotator()
Since you can (probably) guarantee that the HitResult.ImpactNormal is already normalized, you can save a Square Root calculation as well 