Our Priest is from Nigeria... I can understand only about half what he says. BUT... I love listening to him.
My Aunt (RIP) had a very heavy Italian accent.... but what made it even more difficult was that when she got older she mixed English and Italian... not the accent, the language.
She was completely unaware she was doing it.
Interesting Anecdote... My Dad spoke only Italian until he started school. In later life he only spoke Italian with his MUCH older sisters, until they passed. SOOOO... when I took him to Italy in 1971 it was his first trip to the 'home country'. I was excited to have an Italian speaker to communicate while there... but he was hesitant to try thinking he had forgotten too much. He hadn't.
The first night in Italy we went into the Hotel and I forced my Dad to speak to the desk clerk in Italian... which he did. He didn't get 10 words into it and the clerk interrupted him and said, "You're from Lucca aren't you?". I was astounded... Italians can damn near tell which block of the Italian city you came from.