YOU SAID:

I, a person that speaks fluent Japanese, can say konnichiwa!

INTO JAPANESE

日本語が堪能な私は、こんにちわと言えます！

BACK INTO ENGLISH

I am fluent in Japanese, so I can say hello!

INTO JAPANESE

私は日本語が堪能なので、こんにちは！

BACK INTO ENGLISH

I am Japanese is fluent, Hello!

INTO JAPANESE

私は日本語が流暢です、こんにちは！

BACK INTO ENGLISH

I am fluent Japanese is, Hello!

INTO JAPANESE

私は日本語が流暢です、こんにちは！

BACK INTO ENGLISH

I am fluent Japanese is, Hello!