[IfritnoItazura]

Um... The OP is all about communicating better. ◀Take care.▶ (気を付けてください) is just inappropriate as a good-bye in Japanese, unless it's to people traveling in a dangerous zone. Even then, it still doesn't mean good bye--you can use it on the way to a camp surrounded by mean monsters.

◀Detect by sound▶◀Take care.▶

You can't demand a Japanese phrase mean what it does not because the phrase chosen for English can be used in other ways. In any case, just use ◀Good bye.▶ and ◀See you again!▶; the first should work for all languages, and the second definitely works for Japanese.