I mean fail to understand the words in a passage, and fail to express the idea by suitable words, the native englsih speakers often face such problems OR NOT? I really want to know it
I understand perfectly well what you are saying. No one is perfect at all things. Keep hanging around and reading more and you will get better.
For most people, if English is their first language they usually don't have trouble finding the correct words to express themselves. ... I think that's what you're asking.
The op was asking if us English people have issues understanding written posts that have been worded by people who's first language isn't English. Mostly people who don't speak english are doing a very good job, I completely understand that learning and communicating in a language that is not your native tongue, is very hard and I admire people who do this to improve themselves and broaden their knowledge and horizons!