YOU SAID:
hello, i have not seen you in a long time
INTO JAPANESE
こんにちは、私は長い間あなたを見ていない
BACK INTO ENGLISH
Hello, I have not seen you for a long time
INTO JAPANESE
こんにちは、私は長い間あなたを見ていない
BACK INTO ENGLISH
Hello, I have not seen you for a long time
That didn't even make that much sense in English.