Convert non-break space to normal one

sed -i 's/ / /g' *.txt
No space before ,:. and space after ,

sed -i 's/\([^ü]\),\([^ ]\)/\1, \2/g' *-*.txt
sed -i 's/  *\([.,:]\)/\1/g' *-*.txt
No space before opening, after closing bracket

sed -i 's/(  */(/g;s/  *)/)/g' *-*.txt