Buffalo provides Data Recovery services. Read about it here.
It appears that you formatted the drive after inserting it before starting the rebuild. If you have a Windows system available I'd advise wiping that drive, then re-inserting it and rebuilding the array without formatting the drive.Here is the procedure to follow in Windows. https://www.buffalotech.com/knowledge-base/cleaning-a-disk-in-windows-7-using-diskpart