Something someone says in the present can't affect an experience that happened in the past. It can only affect how you presently reflect on that experience...and tbh, the bearing that has on your life is up to you.
And yes, I would count that as canon. If it's in the author's head, it could easily have been written into the story from the get-go (unless you hold that they're no longer sound of mind...); just because they decided to say it offhand years later doesn't automatically make it less valid. You have no way of knowing how long they've had that idea.
But that's the nice thing about fanon: if it bothers you so much, you can invent your own universe where the things you don't like about the canon don't exist. =/
Okay...so? I don't understand why they should be expected to 'do' anything...what's the problem??
Is it just that all of a sudden they have fans from another culture...? Because I don't know how you can live life as a modern content creator with the expectation that only * certain * people will ever be able to view your content...you should be fully prepared to receive attention from anyone on the planet; this isn't the 15th century. An American "weaboo" could always learn Japanese, visit the country, and buy your manga; do they have the right to be your fan then...?
Is it numbers?? Because I can understand being overwhelmed if your fanbase's population suddenly explodes, like going from 100 to 10,000. But simply adding an audience from another country to a healthy existing audience (maybe going from 20,000 to 70,000) shouldn't be that much of a strain on the creator. It's like money; the more you have, the less difference every additional dollar should make.
...That's a good thing, right?