Yes, they are trying to set up a world/story, but so far they have done it in a way that wasn't engaging for me personally. Other people don't have problems with the supposed conflict, though, so I don't hold that as a massive flaw in general terms.
While they may be trying to set up the story and characters through dialogue, the problem is that it doesn't work. This is because everyone talks the same way and everyone has largely the same characters traits (helpful, polite etc), with the only difference level of extraversion (which migh as well just be equated to their barrier to start fucking the MC). I'm almost certain you couldn't tell the characters apart had it not been for the visual elements, so that story building has failed in my opinion.
Are you speculating in whether Mr Dots' writer is a native English speaker? If so, I don't know either, but I would certainly expect it to be someone who is at least highly proficient in the English language, based on their vocabulary and how they form sentances. It is formal and correct, with some relatively advanced words. When someone is not a native English speaker, you tend to have the opposite problem, i.e. that it is very simple and casual with malplaced words that are the result of inadeqaute translation.
Yes, there are differences between UK and US English. However, that is not what I am talking about at all. If you change all the instances of Z to S, nothing changes. If you insert U's, nothing changes. If you add idioms and sayings, there may be interpration difficulties for some people, but they are hardly fundamental to grasp the story. My issue is how formal the characters are, and how unnaturally they speak. That is not a question of subtle spelling differences, but rather your writing style. For example, compare "We need to get out of here and find a place to hide" and "It is of utmost importance that we retreat from this area, and seek a suitable establishment to obscure ourselves". The difference it not one of UK and US English. The second alternative is ridiculously formal, and no one would ever phrase it like that. This is the problem I have with the writing in Sunshine Love.