The following command will change the interface type in the text files, or any other string in the files.
I downloaded the folder and ran the following command from terminal to change all the interfaces from GigabitEthernet1 to FastEthernet0/0 in all the text files in all the subfolders. Run the command from ine.ccie.rsv5.workbook.initial.configs directory in the file system. Hopefully this saves you some time.
sed -i "" -e "s/GigabitEthernet1/FastEthernet0\/\0/"g ./*/*.txt
^find^ ^replace with^
FastEthernet0\/\0 = FastEthernet0/0