It’s okay for things to be ambiguous
It’s okay for things to be ambiguous and you need to rely on your intuition/context to figure it out. There are certain phrases in English that get translated in Japanese in different ways but we see them in our native language (Assuming English, but doesn’t matter) as if they are the same thing. How many times did you debate in English within yourself whether “I know that book” means 分かる or 知っている? Does it matter? No, it doesn’t. You know whether “I know that book” means A or B (it’s actually both) because you don’t care about its Japanese meaning, you care about its English meaning because that’s what you are using: English. (Unless you’re a translator, but that’s a different topic. You are not a translator).
(Related: 知る vs 分かる perspective#)
Take the following sentence:
- “My friend saw his brother at the baseball game yesterday. He was not happy that his team lost.”
Who was not happy that his team lost? My friend? Or his brother?
- “My friend went to visit his dad at the hospital. Unfortunately by that evening he had already passed away.”
Who passed away? My friend or his dad? Well, you can likely infer that his dad passed away, because he was in the hospital.
- “My friend went to visit his dad at the hospital. Unfortunately he got in a car accident on his way there and passed away.”
Who passed away? My friend or his dad? Well, most likely my friend since his dad probably wasn’t in a car accident, since he was in the hospital already.
Context and logic will tell you which phrasing makes the most sense, and if that is not the case then it likely doesn’t matter or the author writes in a bad/confusing style.
This is why it’s important to stop translating and over-relying on literal definitions from dictionaries or grammar guides. You just have to let go and move on, let your general intuition and understanding of the whole passage guide your understanding.
Are there two characters arguing with each other? Someone says something using a word that you don’t understand and the other character gets extremely angry and slaps them? Does it matter what the word actually means? You know that it’s an offensive word given the context and the reaction. That’s good enough for now. Move on. A few months later you might be reading a biology/science article and see that word again used to refer to a certain breed of animal. Well… now you know that word that refers to a female dog can be used to insult people, because you remember (maybe not even consciously) that scene you read a few months back.
Going back to られる of passive vs potential. Again, in many sentences it could be either. Just like my friend and his dad in the hospital. Just like “know” is both 分かる and 知っている. You don’t need to think about whether it’s passive or potential (We don’t really actively think “is this sentence in passive form?” in English either), as long as you understand the meaning of the sentence or, even more importantly, the meaning of the entire passage.
You don’t need to check your understanding. You will know if you misunderstood something because the story you are reading doesn’t make sense (or the person you are talking to will be confused by your reaction). Then you can re-adjust your expectations and figure out where the problem came from (you ask the person to re-word their statement, you re-read a passage paying more attention, you look up a plot explanation online, etc).
Double checking every single sentence with a translation to make sure you understood it is akin to your mother watching a detective movie asking you every 5 minutes who the culprit was or what a certain character’s motive was, before it’s even explained in the movie. Have you ever watched a complicated movie? Have you always understood everything in the plot, even before it was explained to you? A lot of times in detective movies they will show you clues and things that might point towards the culprit/murderer before it is revealed, an attentive watcher might be able to figure it out, but most people probably won’t.
Does that affect their enjoyment of the movie? No, because eventually it will be explained at the end. Does everyone understand the explanation perfectly at the end? No, a lot of people don’t. Sometimes you re-watch a movie and notice a lot of details you missed the first time around. Does it mean the first time you watched the movie the movie wasn’t enjoyable? No. It simply means that you missed some stuff. It’s not the end of the world. Just move on. If you keep watching detective movies you will start to pay attention to certain tropes or common clues, and maybe eventually you’ll figure out who the culprit is before it is revealed in the story. Language learning is pretty much the same thing.
Follow-up: How are you supposed to know if your interpretation of a word or sentence is correct#