That's a good question. I think the sinologist introduced that character originally, possibly as a typo or something. I must have copied it. To be honest, I did

That's a good question. I think the sinologist introduced that character originally, possibly as a typo or something. I must have copied it. To be honest, I didn't even notice the extra stroke in 国 vs 囯. (I do not speak any of the relevant languages at all.) From what I can tell though, the word "nonstandard" isn't very helpful in this context, because there are few universal standards, even when it comes to something as simple as counting strokes. A "nonstandard" character might actually be well-attested in some particular time and place, or in some particular dictionary tradition. I don't know if that applies to this case, but it might.