Yep not fun and definitely the part where the natives know you aren't native. Although from the languages I know, English is the only one that doesn't have the gendered nouns. And then you try Latin, and then every word has a gender and the gendered words also have about 6 different endings based on their position in the sentence if I remember correctly, and maybe even 12 if you also count the plural versions? I could not be bothered with it and dropped it as soon as I could.
Regarding your second paragraph, I think every language has that?
All in all, for most language learning it's better to just learn it in practice. Read and hear the language so much that one thing just feels more natural than the other instead of relying on grammar rules. Won't work in all cases, but at least it will make the learning fun