I think "silly" is the key word here. Jedi seem to be considered mythical, the stuff of kid's stories, not something real. A High Republic world would have routine testing of children for jedi potential at a much younger age, and an important world, a manned jedi outpost.
That latter point is what rules out it being High Republic, essentially, yeah.
There's very obviously no testing, no Jedi presence, no particular regard for Jedi, and the entire societal role the Jedi filled is sneered at openly.
It's also clearly not an openly First Order world, so if it is First Order, it's on the downlow. Which would be a little atypical for either the Empire or the First Order, but not completely unlikely.
It seems more like this may be a bit of a case of:
There's definite evidence of active isolationism. Specifically:
1) The planet has a "barrier" around it - the nature of this is as yet unclear, but what is clear is that people are forbidden from going through it in either direction.
2) Nobody knows where it is, and At Attin has become myth.
3) Little to no real education (or even apparent knowledge in adults) about the rest of the universe.
4) No apparent defense forces except droids nor apparent strategy beyond "the barrier".
It also appears to be:
A) Wealthy - everyone has huge houses and no-one we've seen shows signs of struggling.
B) Really spectacularly badly run - They can't even keep track of kids well, have bizarre policies (-50 points on an exam supposed to determine what you're good at makes no sense at all - indeed nor does a numerically scored exam to determine what you're good at), show clear evidence of nepotism/hereditary positions despite paying lip service to meritocracy, etc. (This is kind of par for the course in SW but they seem pretty incompetent by those standards).
C) Centralized.
D) Lightly populated (though weirdly species-diverse).
E) Apparently didn't notice a massive spaceship landed and sat within a few hundred meters of their apparent capital with the last few decades/centuries.
Also seems messed up to cyborg-ize a kid when they're like 10-12, but they seem to treating cyborg as a race so god knows.