All-caps does *not* signify "don't override this".
PEP-8 specifically says to use all caps to signify constants. What exactly do you think the word "constant" means? I know very well Python doesn't support actual constants and that anything can be overridden.
Your example goes against the convention of using all caps to signify constants and it's a bad design all around. You would be better off with:
def get_emote_lits(root = os.path.normpath(__file__ + "/../emotes")):
... # congratulations, you've re-invented the default parameter in a more clunky way!
I don't know many APIs built around having you fiddle with module-level variables, it seems like an anti-pattern to me.
If "don't change this externally" is the default, why would we have a
naming convention meaning "don't change this externally"?
Modules and Classes and functions typically expose functionality while the purpose of most other objects is to encapsulate state,so it makes sense that attributes would be read/write by default, though some even disagree on that point.
I'm not a hard-core functional programming fanatic, so I'm not about to argue that everything should be read-only by default.
I also think you're playing dumb to avoid confronting my point:
If you found that there was an undocumented module-level attribute in pandas, what would be your initial assumption?
If it's not all caps, is it fair game to override it? Can you re-write your emote code so that it's clear that the emote-path variable is part of the API *without* any documentation?
How much does all caps really communicate?