since there's no discussions at all here yet, I decided to make one for bug reporting, as the comments have a lot of repeating reports. I'll start:
The crossing lanes (the ones that switch sides) in the roundabout module don't detect each other. They just clip through each other. The rest of it is fine. Screenshot: https://psteamcommunity.yuanyoumao.com/sharedfiles/filedetails/?id=2908686128
edit: pedestrians don't have collision either but I think that happens with all of the other ones, too