Re #7 etc.:
Sorry, just in case I sounded harsh as well: It doesn't bother me, personally, which language anyone writes in, as long as I can tell what they're trying to say. And I certainly don't mean only the 100% bilinguals. I'm sure that, for example, if Selima or MiMo or whoever ever did write in English, it would be just fine. (Not to mention considerably easier to read than Swabian, which I can usually figure out about 90% of if I take the time, but I don't usually want to bother. (-: )
That is, I wouldn't like anyone to to think they had to get a new nick and post incognito if they just wanted to practice, just because of the forum convention about using one's own language as the default. To me, being able to recognize the person and have a sense of where they're coming from, their personality as context, is more important -- even though these days there are so few people left with their original nicks.
In the other forums, like Spanish and Portuguese, I do try to write either in German or in the forum language, even though I suspect most people there probably read English as well. I hope it doesn't bug the native speakers too much and that they will correct any glaring errors. But it can be hard to tell, because they seldom answer or seem very interested in discussion, so most of the time I just don't go there much. Maybe it's just that there are fewer people there overall, but it can feel suspiciously like PPP. (Post-posting phobia, for the uninitiated.)
In the English forum, I do sometimes envy people who are not fully bilingual but are still brave enough to try to write in their non-native language (not counting the CC). If nothing else, they're probably learning a lot faster than I am.
But I also sometimes blush for them, and I sometimes have more trouble following their non-native German. I do sort of wish that native speakers would correct obvious errors a little more often, if they had the time. I get the feeling sometimes that people are holding back out of not wanting to embarrass anyone, which is nice and polite, but you can also offer corrections politely.
Strangely, the other way around, the more generally perfect a person's English is and the more carefully they normally express themselves, the more likely I am to correct the occasional small mistake on their part, because I have the impression from their writing that they would want to know.
With my own writing in German, however, sometimes it just frustrates and embarrasses me when I make stupid errors, mistakes I ought to know better than to make, and other people feel obliged to point them out. I wish there were a short way to express "I know you have probably known this basic grammar rule for years and were just in a hurry, but ...," as opposed to "Here's an interesting finer point of the language that you in your tireless quest for improvement might like to become aware of." (-;
That is, I suppose I wish we had a word for Flüchtigkeitsfehler in English. Maybe we could just call them FFs.
But anyway, as long as I still make a significant number of them, and I still have to proofread every sentence and look up vocabulary words, I generally take that as a sign that my practice efforts still belong in the CC. Since I will probably never live abroad, I don't expect that ever to change, but it doesn't weigh on me unduly.