Continuing on this, there might be a bigger issue too, uncertain audience.
First of all it was published on Comic Walker, which is not a yuri magazine obviously, so it being yuri might have turned off some readers, then there's the fact that it's a slow burn yuri, which is not for everyone too, and then there's the fact that it has quite a focus on the fantasy side and the lore, which might turn off people who only care about the yuri.
Second, the yuri, or just the romance as a whole really, might have turned off people who was interested in the setting and lore.
Honestly, although there is quite a focus on the fantasy side, this is first and foremost a slow burn yuri, so I can't help but feel being published in anything but a yuri magazine was the main issue behind low sales, yuri fans will read virtually anything as long as it's not outright garbage, but publish a work like this in any other magazine,
who exactly is the audience they're aiming for?
Unfortunately general public won't get into stories like this, one could argue it was doomed from the beginning in any non yuri magazine.
And as someone basically said, this probably works better as a Twitter/ Pixiv manga, with the author releasing chapters when they believe it's done instead of following a magazine schedule, unfortunately not all digital mangas work as well when published in magazine.
TLDR
I'm fucking pissed cause most Japanese only want easy to digest brainless self insert and or escapism mangas