YOU SAID:

i'm bored and sitting on a board. They're sitting on their board while being bored.

INTO JAPANESE

私は退屈してボードに座っています。彼らは退屈している間彼らのボードに座っています。

BACK INTO ENGLISH

I'm bored and sitting on the board. They are sitting on their board while they are bored.

INTO JAPANESE

私は退屈してボードに座っています。彼らは退屈している間、彼らのボードに座っています。

BACK INTO ENGLISH

I'm bored and sitting on the board. They are sitting on their board while they are bored.