Does legalization/Apostille certification help avoid submitting additional documents?

Hello everyone. I'm applying for FBR through my grandmother. I currently have birth certificates for three generations of my family. Two are from a Hague Convention member state, and one is from a non-Hague Convention member state.

I know that foreign documents don't require apostille.

I'd like to know if legalizing the birth certificate would help avoid potential requests for additional documents?

Also, what kind of translator should I choose for non-English documents? Are NAATI-certified translators acceptable?

Thank you all for your kind replies.