Standardise leading zeroes in an input string
Ruby, 111 bytes

I hope this catches all the details of the spec

puts $*[0].gsub(r=/(?&lt;![^,\s])(-?)(\d+)(?=\.?\d*(?![^,\s]))/){$1+$2.rjust(i.scan(r).map{|m|m[1].size}.max,'0')}


It reads the input as the first command line argument and prints the result to STDOUT.