Download and run the following script to recursively convert soft tabs to hard tabs in plain text files.
Place and execute the script from inside the folder which contains the plain text files.
#!/bin/bash
find . -type f -and -not -path './.git/*' -exec grep -Iq . {} \; -and -print | while read -r file; do {
echo "Converting... "$file"";
data=$(unexpand --first-only -t 4 "$file");
rm "$file";
echo "$data" > "$file";
}; done;