However, computeMeshVolume() gives me 0.329
I’ve answered this and where the function comes from in your previous thread. It’s possible that answer from the stackoverflow thread is incorrect or has other issues I’m unaware of such that it should be removed. It’s worth looking into but it’s not a high priority at the moment. As I’ve mentioned before you are free to help investigate these problems, as well.
Also please provide example demonstrations of your code with jsfiddle. People should not be expected to recreate your issues in order to help.
Some of the edges appear not to be 2-connected.
There has never been a guarantee or requirement that all edges have a 1-to-1 connected sibling.