The security flaws found by that independent review aren't particularly worrying.
Clearly there are improvements that could be made but almost all of the problems that they found were procedural and the ones that were technical amounted to "if I can control the server I can control all the votes" or "if I can control a user's computer I can control their vote", which is not a surprising outcome.
If I control the vote counting depot I also control all the votes, if I coerce a person I also control their votes. We have dealt with these problems for more than a century, we can deal with them in an online context.
Clearly there are improvements that could be made but almost all of the problems that they found were procedural and the ones that were technical amounted to "if I can control the server I can control all the votes" or "if I can control a user's computer I can control their vote", which is not a surprising outcome.
If I control the vote counting depot I also control all the votes, if I coerce a person I also control their votes. We have dealt with these problems for more than a century, we can deal with them in an online context.