Yes, I was wondering about that worry as well. It is extremely unlikely to fail N1 only because you had problems with obscure kanji. It is good to have a look at them of course, but there are more fruitful ways to spend your preparation time. Even the people designing the tests would know it was just malicious to keep asking foreigners stuff you don’t need in daily life.
On the positive side after you reach level 60 (or rather say 30–40) it is easy to learn any missing ones (it’s not a shame to be a completionist). You already know all parts the kanji are constructed of, they are often semantic-phonetic compounds, and they are more regular in that regard. You won’t ask yourself the question “how do I learn the rest?” then, you can just do it.