If loucha is on Antimatter legion side, can it be that he smuggled Jingliu into the Zianzhou Alliance with his casket?
That's why we never see him going anyway without his casket,... except in the shackling prison, where Jingliu is also there?
It's also why Jingliu is in the Exacting Santum, the same place loucha were.
In his companion mission, he also don't carry his casket, which mean he left it somewhere... Is it by any chance it's after the shackling prison incident? (because he left after that, so he can't be in the shackling prison)
So we have a timeline.
Loucha went to the port. Left Jingliu there.
->
He found Sushang and Dan Heng at the port
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Jingliu met Yanqing and challenged him (yanqing companion quest)
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When Dan Heng left, He came back to pick up Jingliu.
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They came to Shackling Prison to convince Jing Yuan to join them, or maybe break blade out? (Shackling prison incident)
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They seperated paths. Loucha helped Back'n and Forth then throw his casket at some random place (happened in his companion quest)
->
Leave.
Sorry for bad english.