[There's a lot to go through here. But firstly...

Xichen's baby bro here - you can tell because of the calm demeanor and the forehead riboon]

Xiongzhang does not prefer large celebrations. But if there is someone who can help me with the kitchen, I would like to prepare tea and his favorite cakes.

[No, he doesn't understand how private messages work, and anyway, it's not like Xichen doesn't know Wangji will do this. So there's no point in trying to surprise him.]