Both Taylor and Hana just call the beings “entities”, which, while not very specific, is suitably mysterious if you proper noun-ize it. “The Entities”. Much better than tessaractids, don’t you think?
I mean, if you’re going for mysterious, sure. I did come up with the name tesseractids explictly to have a better way to mention them than with extremely nonspecific terms like “beings” or “entities”, though.