"저는 매주 일요일에 늦잠을 자요."
Translation:I oversleep every Sunday.
The way I conceptualize it, oversleeping and sleeping in has to do with intention. If I overslept, it was unplanned, unintentional, probably a mistake. If I slept in, I probably plan to do so or wanted to do so. "Oh no, my alarm didn't go off and I overslept!" "It's going to rain all weekend so I'm going to sleep in tomorrow morning."
This sounds like a translation issue.
"I sleep late every Sunday" only means in the morning, in English (in my dialect anyways).
To say that one sleeps at a late hour at night would be "I go to sleep late every Sunday."
This seems to be a situation where direct translations will fail.
Oversleep/slept, meaning sleeping/having slept past the time you planned to awaken, gets 두번 자고하/했다 as I was reminded by my daughter through the Japanese.
I never liked just "sleep late" either for that very reason. We say, "sleep until late" or "sleep in". Memrise rendered it "have a lie in" and it's been a long, long while since I've heard that . . .