To measure how secure the resulting code is, have a test suite of malformed packets or other input and see how many of them the code in each language handles.
That measures how well a particular developer takes, with some noise induced by the working environment (say there's construction noise during python week, not during java week, or more meetings one week than another, or the developer's has relationship troubles at home). Randomness happens.
Deducing a number that's more generally valid requires having n workers doing the same work and then doing statistical analysis. Happily that also takes care of the single-worker problem. Still, the cost of the experiment easily rises by a factor of twenty or a hundred, depending on how well the noise can be controlled and how much accuracy is needed.
Asking for improvements that would increase the cost of an experiment by many thousand per cent is a %$#@!%#@! $%#@!%@#$ thing to do. IMO.