I’ve only reached level 8 and I’ve already come across 4 or 5 different ways to say “foreign” meaning ‘outside of the country’ and not just ‘unfamiliar’ or ‘strange’.
It would help to specifically mention the words you find confusing.
There are only 2 words here that literally are just the adjective “foreign” on their own, 対外 and 外来.
If you meant why are there many words that are in the format “foreign something” this has more to do with how the language works generally, making things that would be phrases in English into compound words.
I think the fact that Japan is an island and that their civilization spent a good deal of its history isolated from other countries might have something to do with it. But really, languages tend to have lots of synonyms for things. There may not be any particular reason for it, any more than there’s a reason we have so many synonyms for “big” in English. Big, giant, huge, enormous, gigantic, titanic… probably others I’m forgetting.
Porcino, marrano, cerdo, chancho, puerco = pig
They are just synonyms. Some things have multiple ways of expressing them : )
Like overseas, abroad, outside, expat, offshore, exotic?
Oh, sorry, that’s English.
But seriously, there’s going to be a clumpiness to vocab because of compounds using the same or similar Kanji. Wait till you get to “expectation”
Maybe I was so used to seeing the word “foreign” that those other words couldn’t come to mind.