Could you get the final confirmation from Aさん that this interview date is fine for him/her?
Would you make sure with Aさん one last time whether the date works for her/him or not?
ご質問ありがとうございます。
① "Could you get the final confirmation from Aさん"=「Aさんから最終確認を取ってくれますか」
"that this interview date is fine for him/her?"=「この面接の日で問題無いかどうかを。」
② "Would you make sure with Aさん one last time"=「Aさんに最後の確認をして頂けますか」
"whether the date works for her/him or not?"=「その日が都合が良いかどうかを。」
ご参考に。