How should I flag a meeting conflict in a shared calendar at a Korean workplace?

Flag the clash promptly rather than silently declining one invitation. A practical approach is to tell both organisers that you have a conflicting invitation and ask whether your attendance is essential or whether one meeting can move. If both need you, or you cannot judge the priorities, ask your manager to decide. Your team's calendar practices matter more than a supposed rule for all Korean workplaces.

You could write: 'Thank you for the invitation. I have another meeting at the same time and am checking which one I should attend. Is my attendance needed for a decision, or could I send an update in advance? If a change is possible, I am available on [date] at [time] or [alternative time].' To your manager, briefly name the two meetings, their purpose, and any decision that depends on you, then ask which to prioritise. Share only details the recipients are allowed to see.

Use a tentative response while the conflict is being resolved if that fits your team's practice, and add a short explanation. Once the priority is agreed, update both invitations and tell the organiser of the meeting you will miss how you can contribute or receive the outcome. If your calendar has a propose-new-time function, use it with a message; the organiser still needs to accept the change. Do not move a shared event yourself unless you are authorised to do so.