• Ṣaḥīḥ li-ghayrihi: the starting point is ḥasan li-dhātihi; other transmissions compensate for lesser precision.
• Ḥasan li-ghayrihi: the starting point is a weak report; other transmissions remove the weakness within the limits explained.
The names are not interchangeable. Not every weak report automatically becomes ḥasan, and several translations of one sanad are not other chains.