I'll just restart my playthrough. What can I do to avoid softlocked again? When everything stopped happening, here's how far I had gotten: Quest 14, all trainings up to Sound Chakra, Asami to flower 3 plus the scene at her house, talked to guru pathik, all opal scenes, pema breast scene.
If you have already helped Lin with interrogation and read those two letters (That pema gave) from pathik, lin will come to airtemple island at evening, and then next day, you can start quest 15