YOU SAID:

I wish i was better at singin whil playing the piano.

INTO JAPANESE

私はピアノを弾いている間、私が歌うのが上手だったことを願っています。

BACK INTO ENGLISH

I hope that while I was playing the piano, I was good at singing.

INTO JAPANESE

私はピアノを弾いている間、私は歌が上手だったことを願っています。

BACK INTO ENGLISH

While I'm playing the piano, I hope the song was good.

INTO JAPANESE

私がピアノを弾いている間、その曲が良かったと思います。

BACK INTO ENGLISH

I think that song was good while I was playing the piano.

INTO JAPANESE

私はピアノを弾いている間、その歌は良かったと思います。

BACK INTO ENGLISH

I think the song was good while I was playing the piano.

INTO JAPANESE

私はピアノを弾いている間、その曲は良かったと思います。

BACK INTO ENGLISH

I think the song was good while I was playing the piano.