Your incredible literal-mindedness and over dependence on understanding (or verifying your understanding) through translations hold you back.
How any native speaker can say something like "I'm so happy I can't stand it" is contradictory and ambiguous is totally beyond me. What must run through your mind when you hear things like "Boy! It's colder than hell outside!" or "This tastes like sh*t!"?
Seriously, you need to loosen up and develop the ability to pick up on the "feel" of usage from context instead of tripping over every square Japanese peg that can't be pounded into a round English hole.
I suspect you have probably also developed a severe habit of and addiction for translating, which is fine up to a point but which very quickly turns into a crutch and can end up permanently hobbling your progress. Read Japanese in Japanese as Japanese. Understand it the same way.
You mentioned earlier that you have some reading material but don't feel ready for it yet. I am reminded of my dear 72 year old mother who to this day can't swim because she heeded the words of her own mother, who told her never to go in the water until she knew how to swim. You need to at least partially set aside this grammar-translation method (which is used to horrible effect in teaching English in Japan) and force yourself to pick up some of those short stories and force yourself to NOT TRANSLATE in your head and to look up NOTHING WHATSOEVER and develop the skill of figuring things out from context and repeated exposure in varying contexts, and how to be comfortable with getting the gist and general idea of 80% of something rather than wanting the detailed particulars of 100% of everything.
Those are skills entirely separate from the knowledge of kanji, vocabulary, and grammar. And they are ESSENTIAL skills if you ever plan to do anything with all this Japanese you're studying other than just treat it as an interesting academic exercise.
You've already given this なる thing about 10 times more thought than it deserves or is necessary. All that is required when you hit things like that is that you make a mental note of it and be on the lookout for future instances and use them to broaden the base of experience you use to develop a "feel" for the meaning and usage. You don't have to have a rational understanding of every little thing that passes before your eye. You only have to understand the "what" and the "how" of usage....not the "why". This is what they say. This is how they use it. Now I can use it too. THAT is how you effectively learn Japanese as a second language. I'm going to fixate on and get stopped by every little thing and insist on understanding it through rendering it into English is how you learn Japanese as a foreign language.
You've stared at the water and examined every grain of sand on the shore long enough....jump in the ****** water and swim already.
