English is a difficult language to adopt as a second language for so many reasons.  Your point about learning Japanese is irrelevant to this 'why English is difficult' conversation.  In places like Canada, did you know the reason for having so many different newspapers is because of the reading level that each one has adopted?  The lowest  reading level being that of a fourth grader.  English has tenses, which in turn, all have subtenses (past, past continuous, past perfect etc.) Like the first quote, if two words have the same spelling, it depends if it is a verb or a noun for how it is pronounced.  And yes, it does matter how coherent and fluent you are in English because when you don't have your prepositions, conjunctions, articles and you use the incorrect tenses and/or verbs then guess what.... I have no freaking clue what you just said to me.  With communicating in any language, the point is to get a message across, and to do it in English is difficult.   Idioms are the hardest to understand because you can't even look in a dictionary to find out what it means.  Also, different people pronounce the same word differently. Example, aluminium can be pronouned with 5 syllables or 4, both putting the stress somewhere different in the word.   I can spell a word as center or centre, meter or metre, humor or humour, favor or favour and guess what.... it's the same word.   I can write about this stuff all day because you know what, I am a native English speaker and growing up I used to ask the same questions and sometimes your answer will be, 'It just is' and there is no logical answer behind it. 

Des