[X] or [X+1] [noun]s

A turn of phrase I've noticed recently, although it seems old-fashioned (or possibly British) is "[X] or [X+1] [noun]s".

Examples:
- "An army of 300 or 400 soldiers."
- "I drove there with 2 or 3 friends."
- "The house had 13 or 14 windows."

This turn of phrase is interesting to me, because I think it has connotations and I can't tell what they are.  I suspect it's not (or perhaps not always) literal - like how "a dozen eggs" means literally 12 eggs, but "a dozen people in line" can mean 10 or 14.

Does "300 or 400 soldiers" mean between 300 and 400?  Or might it be 298 or 407?  Or might it be between 300 and 500? (i.e. "three hundred and something or four hundred and something")?  The speaker knows, I can't tell.

The "2 or 3 friends" phase is a real-life example, i.e. someone actually said that. (Unfortunately, I didn't save the source.)  That's a situation where they'd actually know the real number - surely when it's only 2 or 3 people, you can remember who exactly was there.  So why did they phrase it that way?

This sounds like a strange thing to worry about - even if I don't know what the speaker's thinking, it's clear enough for our purposes - but this kind of thing is sometimes relevant in translation, when the target language doesn't do the same thing with numbers or doesn't have the same connotations.

For example, in French they have the word dizaine, deriving from dix, meaning 10. As I mentioned above, in English we have "dozen", which means either "12" or "approximately 12" depending on the context. (French also has douzaine, meaning "dozen".) Dizaine does the same thing with 10 as "dozen" does with 12 - it either means "10" or "approximately 10", depending on context.

But because English doesn't have a word for dizaine, the French to English translator needs to figure out from context where this particular instance of dizaine means "10" or "approximately 10", and whether the approximateness needs to be explicitly stated in the translation. (For example, if I say "Cassandra can cook Thanksgiving dinner for 10 all by herself!" and there were really 11 people at dinner, no harm is done by my saying 10. If I say "Cassandra invited her 10 nieces and nephews to Thanksgiving dinner" and Cassandra actually has 11 nieces and nephews, someone might read that and wonder whom Cassandra has disowned.)

This doesn't seem like it would be relevant to translating "[x] or [x+1]" - all languages have words for numbers and for the concept of "or". (And if there are any that don't, please let me know in the comments!) You can just plug the words for the numbers and for "or" into the sentence, and the translation is complete, right?

Not necessarily.

It's possible that a number phrase that's perfectly cromulent in one language might sound unduly weird in another, and the translator might have to adjust.

An example I routinely encounter in technical and administrative documents written in French is an approximating adjective followed by a non-round number, for example environ 473 voitures ("around 473 cars").

It is a simple matter to translate the words, but it sounds conspicuously weird to the English reader in a way that it doesn't to the French reader, so the English translator has to figure out the connotations (do they mean literally 473 or approximately? If they mean approximately, how did they land on that number rather than 470 or 475?) and the implications (what would be the consequences if you said "473" without any modifier and it turned out to be approximate? Or vice versa?) and adjust their translation accordingly, or find a workaround. (I like "some" as a workaround here - "some 473 cars". It conveys the notion of approximateness, but is also more easily overlooked by the English reader).

There might be some languages where "300 or 400 soldiers" also sounds conspicuously weird in a way it doesn't to the English reader, so a translator working away from English might need to understand the connotations so they can eliminate the conspicuous weirdness without eliminating accuracy.

And that translator may well ask me, in my capacity as a native-speaker Anglophone, exactly what the connotations are.

And I haven't a clue! Isn't that weird?