This is not as big a deal as it is reported. First of all, it is only about summing the votes and secondly, all the original reports of ballot counting of individual polling stations are published (on the website) of municipalies and as Election Markup Language files. The summations are also published in this format. It is relatively easy to verify the summation. I actually wrote a program for doing this for the province I live in. See:
https://www.iwriteiam.nl/D2305.html#26 and previous blog entries.