Although I haven’t been long with AA community and a total newbie, my humble opinion…
In my perspective this is now Chinese territory (as long as Calcutta is in Axis) hands and therefore normally subject to page 21,
“If the original controller’s (the power whose territory you just liberated) capital is in enemy hands at the end of the turn in which you would otherwise have liberated the territory, you capture the territory instead. You adjust your national production level, and you can use any industrial complex, air base, and/or naval base there until the original controller’s capital is liberated. The capturing player can’t use these newly captured facilities until the player’s next turn.”
However, China is not an Industrialized nation, and have a special rule set applied! Any other nation could benefit from this paragraph, and make use of the complex…the opposite is true regarding China in my opinion.
Page 10 states the following; “If a Japanese industrial complex is built on a Chinese TERRITORY and that territory is later recaptured by the Chinese or liberated by another Allied power, the industrial complex is removed from the game.”
A Chinese territory cannot hold an IC, irrespective of former ownership, as I see the rules.😊