Short answer: Yes (asset #23137799)
Long answer: Oh god.
So, I went to search for a scene to link to show proof, and found this. (BA Volume F spoilers, obviously)
However, she's called Kay there.
I then booted up Blue Archive to check just in case that it was really just me, ready to admit my mistake, and lo and behold - asset #23137799 (and Aris calls her Kei too)
The wiki is unhelpful because it doesn't list the official translations and only uses their own, on Reddit the only thing I'm finding are posts which just call her all three variations at the same time, and I can't find much information online in general.
What I assume happened was that during the first release her nickname (ケイ, lit. Kei) had been officially localized as Kay, but then it got changed to Kei in a later update. (For reference, we're already prioritizing official translations by using Aris over Alice/Alis/Arisu/Whatever other spelling people conjured)