Most of the conditions you mentioned look okay to me, except these. Some members registered a long time ago but didn't make much effort to learn about the forum and Bitcoin. Such people might not contribute knowledge to the forum because they lack the knowledge. If you are not learning and relearning you will not be relevant here.

Yeah, members are expected to communicate in good English, especially on the global board. However, it is not a criterion to know the quality of posters. Many good posters are not from English-speaking countries, but they give out quality information. The most important thing is to ensure that your writing is simple and relevant. Good grammar is important, but it wouldn't stop you from contributing to the forum.

I think one of the ways of knowing a quality member is impact. And sometimes the you can identify such members when they make announcements about leaving the forum. The reaction of members of the forum will show you how important they are in the forum. An example is Lauda and o_e_l_e_o