Question

I am a manager in charge of import and export trade. Is it proper English to call me oversea manager? For reference, I am a Korean English learner.

Answer 1

No, oversea manager is not proper, but you can say you are the manager in charge of import and export, just as you rightly said above

Answer 2

No, "oversea manager" is not proper English. A more appropriate title for your role would be "international trade manager" or "import-export manager."