Theory: perhaps the letters do not have phonemic content?

[ololololo]

If its topic turns out to be about summoning demons, divine revelations or plant magic rituals, the impracticality could be an essential part of the process.

I was thinking at my leisure...
The problem with the theory of artificial language is that there is no proper methodology. If this is indeed an old conlang, then logically, the content of VMS is probably mystical, but more so with an alchemical twist. Therefore, it is more likely to be an alchemical language rather than a philosophical one.
If this is the case, then I assume that this language is very limited and incomplete compared to other languages, but it is also rigidly functional, meaning that it can be used to describe what is described in VMS.
It would be possible to study the functionality of such a language, but this job is definitely not for me...