When and what are the holidays associated with lounge and steamworks trinkets? Are they even two different holidays?

Also, Luminiere starts on december the first and effectively ends on the 31st of december. But when do the other holidays begin and end, like Morostide, Vesnali and New Years? For example, is Morostide the whole of October? Or just one, two or three weeks?

The lounge and steamworks trinkets are both associated with the same holiday, the Atebus Masquerade that happens in March.

You can find a full holiday schedule in the Subetapedia, under the Subeta navigation tab at the top. Click on Holidays to read about the different ones or see the schedule.