I had a look at your files. GreatRespublic.eu4 consists completely of NULL bytes and the second half of GreatRespublic_Backup.eu4 are also NULL bytes. I don't think that there is enough information to restore a working save from the other half.
AFAIK these NULL bytes saves happen if the computer has been switched off before the save was fully written to an SSD. One reason for this can be a power outage or empty battery. But it can also happen if you configured windows to use a write cache(especially the setting “Turn off Windows write-cache buffer flushing on the device”)