The test is not complete. Checking only 20 of the 24 variants, I easily pass all the tests. Here are the sides I verified (side-by-side recordings):

[ '1243',
  '1342',
  '1546',
  '2134',
  '2431',
  '2536',
  '2635',
  '3124',
  '3421',
  '3526',
  '3625',
  '4213',
  '4312',
  '4615',
  '5263',
  '5362',
  '5461',
  '6154',
  '6253',
  '6352' ]

As I understand it is the case when the cube turns 90 counterclockwise. But I just can not think up examples to close this gap.