Unforeseen Consequences, Katawa Shoujo Forums Edition

[Mirage_GSM]

Actually, I think most Scots' native language is Scots, which is mutually intelligible with English, but still considered a separate language.

I'm actually amazed that you found an explanation that at least makes a modicum of sense - though I don't believe you came up with it beforehand...
Also if it's Scots, then it is irrelevant to translation issues, because whether or not it is considered a seperate language linguistically it is so close to English that it simply does not matter.

Even so, his world is slightly different from ours. Differences will become more apparent as the story progresses, but that's one of them.

Again: If your world differs from the real world in any significant way, you have to tell your readers - preferably IN the story and not in a comment after you've been called out on it.
If you drop subtle hints in the story you will be praised for your foreshadowing when the reveal comes later. If you do it this way it just sounds like a cheap excuse - especially if there seems to be no story reason for such a difference but to excuse some other discrepancy that came up.
Oh, and if in your world Japan happens to be publicly ruled by the aliens that came to earth three years earlier, you might want to address that before it becomes an issue.

[Emps]

Even so, his world is slightly different from ours. Differences will become more apparent as the story progresses, but that's one of them.

Again: If your world differs from the real world in any significant way, you have to tell your readers - preferably IN the story and not in a comment after you've been called out on it.
If you drop subtle hints in the story you will be praised for your foreshadowing when the reveal comes later. If you do it this way it just sounds like a cheap excuse - especially if there seems to be no story reason for such a difference but to excuse some other discrepancy that came up.
Oh, and if in your world Japan happens to be publicly ruled by the aliens that came to earth three years earlier, you might want to address that before it becomes an issue.

The problem is introducing those changes in a way that would make logical sense without interrupting the story, especially at this early point. I can change things to show their world is different (such as Presidential candidates), but there isn't really a good way to show that the Gaelic languages are more alive in the British Isles when, at that point, the story is in Japan.

[Hanako Fancopter]

Even so, his world is slightly different from ours. Differences will become more apparent as the story progresses, but that's one of them.

Again: If your world differs from the real world in any significant way, you have to tell your readers - preferably IN the story and not in a comment after you've been called out on it.
If you drop subtle hints in the story you will be praised for your foreshadowing when the reveal comes later. If you do it this way it just sounds like a cheap excuse - especially if there seems to be no story reason for such a difference but to excuse some other discrepancy that came up.
Oh, and if in your world Japan happens to be publicly ruled by the aliens that came to earth three years earlier, you might want to address that before it becomes an issue.

The problem is introducing those changes in a way that would make logical sense without interrupting the story, especially at this early point. I can change things to show their world is different (such as Presidential candidates), but there isn't really a good way to show that the Gaelic languages are more alive in the British Isles when, at that point, the story is in Japan.

To me, this seems like a fairly minor detail that doesn't really bear too much consideration, as without Googling the subject I doubt many people would notice it as inconsistent with real life in the first place (I certainly wouldn't--if someone told me there are still communities of Gaelic speakers in Scotland, I wouldn't know any better). With a small issue like this which is not really plot important, I prefer to just change it if someone says something, as that's usually the easiest response. But if you don't feel like changing it I think the best thing is to just say "yeah, my story's world doesn't match the real one 100%, them's the breaks." For instance I ended up putting a note on my fic that the dates of specific events might not match up with the canon to head off nitpicks over them.

[Mirage_GSM]

The problem is not that the story deviates from the real world in some ways. As you said those differences are minor, and I wouldn't have mentioned them myself.
The problem is that those deviations are used as explanations/excuses for real plot problems that do arise in the story - and in this case that they do not even really help to resolve those problems.

Ths whole discussion started when I pointed out that his character was exhibiting various Mary Sue traits, and with each attempt of the author to justify those things the whole thing got more and more out of hand...

[brythain]

It's entertaining when the discussion on the story exceeds the story length. Means a learning point exists for everybody.

[Oddball]

This is certainly better than your first attempt at the story. However while Angus is now a far more less cliche character, he also tends to lack a lot of personality. The fact that he's able to walk around, talk, and hang out with the main cast with no real problems makes him feel less like a foreigner and more like somebody that's been a student at yamaku for years and we were just never introduced to until now. More often than not, it seems like he's just wandering into one encounter after another with no real purpose.

As for his language skills, if he's not supposed to be great at Japanese, have him talk like somebody who's not great at Japanese. Sort of like how you see in movies where characters aren't supposed to know good english.

Like for instance my opening lines here would be something like "This certainly better than first attempt. Angus less cliche. Also lack personality." Perhaps not quite THAT over the top, but something closer to those lines.