Jumping on to this thread as I have a similar question.

I have a China Airlines business class flight in Q1 2024 from Hanoi to Taipei. Anyone know which lounge I have access to? Is it the Vietnam Airlines Lotus Lounge, since China Airlines is a partner SkyTeam member? However, the SkyTeam Lounger Finder webpage (not particularly useful) only lists this one lounge in the Domestic Terminal for three airlines: Air France, China Eastern and Vietnam Airlines two of which are overseas airlines(!). So nothing for China Airlines (nor Korean Air and XiamenAir for that matter). I arrive into Hanoi on a long haul Vietnam Airlines international business class flight so transit lounge access would be very welcome.