BS”D
While looking for Hebrew roots to all words in all languages may be going too far, keep in mind that:
1) Jews lived all over the world.
2) Jews were traders and professionals – and usually very literate, which was one means of rising to the top until the next tzoirer came along.
3) At one time the Torah was studied in the original, by non-Jewish scholars and those studying to be galochim (lehavdil). Laha”k (not the jargon of Ben-Yehuda OLBM) was considered a classical language along with Latin and Greek even in US Colonial times, hence the laha”k on the shields of Yale and Columbia universities.
So, what does exist is Hebrew slang in other languages, such as this “copacetic” that seems to be confirmed, as well as “haver” for friend in Hungarian, which is even heard in commercials today, some slang words in Dutch etc. Mouse from mius seems a bit far-fetched.