Don't worry about it. I can totally see how it'd come across as a bug (it's not the most easy to read script).
in case it helps here's a few evaluation examples:
all_state = { (Everything inside the {} associated with this statement is checked for every state in the game in turn. If it is true for every state this statement evaluates as true)
OR = { (Out of all statements contained in the brackets associated with this statement if at least one is true, this statement is true.)
state = 341 (True if state is istanbul)
NOT = { is_core_of = GRE } (True if not a greek core)
is_controlled_by = ROOT (True if owned by you)
} (closes the OR statement. As there are no other statements directly "under" all_state, this OR statement is all that gets checked for every state)
} (Closes the all_state statement. So everything above is checked for all states)
For instance if we evaluate this for Istanbul when held by turkey we will get:
OR = { (True as one of the contained statements is true)
state = 341 (True, as the state is istanbul)
NOT = { is_core_of = GRE } (False, as the state has a greek core)
is_controlled_by = ROOT (False, as Turkey, not you controls the state)
}
Similarily doing this for athens when held by Yugoslavia will return
OR = { (True as one of the contained statements is true)
state = 341 (False, as the state is not istanbul)
NOT = { is_core_of = GRE } (False, as the state has a greek core)
is_controlled_by = ROOT (True, as you control the state)
}
Again doing this for Crete while controlled by Greece will give
OR = { (False as none of the below statements are true)
state = 341 (False, as the state is not istanbul)
NOT = { is_core_of = GRE } (False, as the state has a greek core)
is_controlled_by = ROOT (False, as you don't control the state)
}
And finally for say, london while held by england:
OR = { (False as none of the below statements are true)
state = 341 (False, as the state is not istanbul)
NOT = { is_core_of = GRE } (True, as the state lacks a greek core)
is_controlled_by = ROOT (False, as you don't control the state)
}
So these are the evaluations that are done for every single state in the game to check if it should give you the achievement. Only if it come out as true for every state the "all_state" (As the OR statement is "contained" within it and the other 3 statements are "contained" within that) statement will return true and you'll be eligible for the achievement (if you fullfill all the other "all_state" parts as well)
I hope this helped clarify things and didn't come across as condescending.