Welp Night is one of my Waifu candidates, thus i simply have to say that she is one of the prettiest knights in her evolved form. I only wish she whould speak a bit less about cleaning though :X. And yes this is purely subjective and should thus be avoided to say since it only leads useless debates. But where should we praise our waifus, if not here.^^
That being said, I think she is a rather good knight, though obv not among the best. She has great stats for a 5* unit, with more than 6k attack and more than 13k hp. Since her attack stat is nice and she has an attack buff, her lifesteal isn't without value.
I'll probably change my Solar Blast Squad in the future into the following: Night, Violet, Poinsettia, Fir and Peach. All of the units have an attack buff and increase either Solar Blast damage or increase crystal drop. Thus she surely isn't without value.

My opion of Lupine isn't as high though. Some time ago, I did a bit of testing with crit and it seemed rather underwhelming. A normal 5* attack buff seems way better. But I heard it shall be reworked sometime in the future, so maybe she'll get better then.
Furthermore her Hp is rather low for a 5*. On the other hand she has the usual gacha attack buff (which is usually stronger than the event attack buffs) and has an aoe ability.
So in my opinion it's pretty much dependent of how strong the competition is, if u're deciding wheter you have use for her or not.