You well mentioned about other higher priority in the life and do not wasting time on too many details of second languages however if someone want to immigrate to another country with different language and probably having a job, details(language) come to the priority. Its better to say with second language you may have more limited options in all aspects of life. My point refers to the part of life which more related to the culture ,language etc. Ex: A second language person may be a solicitor or psychologist but of course he/she is looser in competition with first languages because these field of study or work is highly influenced by language. However for some non-linguistic field such as hand jobs ,technology, medicine or anything that is not based on language competition is quite easier. Even some sectors are local (ex:law, psychology..) Thats why I think you may learn a second language for experience or maybe research or fun but it is not possible to speak as native language and your life might be more restricted in terms of lots of things.

Yes - if you move to another country where you need to use a different language, you're going to be at a disadvantage for a long time, but you can reach a point where you speak the language well enough for most jobs to be open to you, and people aren't worried about small errors so long as the meaning is clear. I know people who have moved to my country without speaking good English but who now speak it better than many native speakers after just a few years, though still with a hint of a foreign accent.

Perhaps there's some luck involved in this though, because it may depend on them having enough friends who correct all their errors to help them learn. Most people are very reluctant to do this as it feels rude to keep pointing out errors. There are also cases where the error itself may be so rude that they don't want to let the person know what they actually said. There's an example of that in your post above where you refer to "hand jobs", and I don't want to tell you what it actually means (but it's often done with dogs to help them breed without meeting each other). I'd advise you to refer to manual labour instead.

You need to make sure all your native-English-speaking friends know that you want them to point out all your errors, and keep reminding them of this if you think they're missing any. There can also be difficulties in finding enough of the right friends if you live in a place with lots of immigrants who don't speak English well enough to notice the errors, and in situations like that, errors can be spread from person to person, appearing to be correct because so many people make the same mistakes. This can be made worse if the few people around who are native English speakers are racists, so it's easy to be trapped in an environment where you don't have access to the help you need.

The Internet can help though if you can find the right contacts there. I'm happy to continue a conversation with you here if you want to give it a go (although I only look in here once a day, so it'll rarely be more than one post per day), and I'll correct everything and help you learn better ways to say things. For example, with "Forget about common exceptionals, your fortune influenced by mother tongue language", I don't know what you mean by common exceptionals/exceptions, and when you say "fortune", I think you mean "success". "Fortune" tends to mean "wealth", but it can mean "success" and "failure" in some contexts, such as where a "fortune teller" stares into a crystal ball (a ball made of glass) and makes predictions about your future. "Fortunately" means "lucky" (a good outcome by chance).