Well I just sat through this, and thought it was pretty ok in showing what it might look like being in a closed coven (masquerading as a dance academy).
Since it is a horror film, it did accentuate some elements of the witches' practices and malpractices. For the most part, it is also unsure what stream of witchcraft
they were practising, but from my very basic research, it is confounded with a (fictional) goddess cult, primarily based on three mothers, one being Mother Suspiria (Mother of Sighs)
However, what I found to be most interesting is the use of dance & bodies. while most practising today rely on visual + language to cast a spell, the film shows that the main dance titled Volk, is itself a spell in dance form.
As everything we do is centred on Intention, I don't find this to be a stretch at all, although the logistics to perform this complicated dance-spell would mean that it is not an easy one to cast - in terms of number of participants & technique of performance.
Another draw is Tilda Swinton, who plays THREE roles in this film - see whether you can spot them!