I remember it being interesting to work on. It's been years, but if I remember right, there is some way to convince the game to dump a log of unit positions during a multiplayer match, possibly as part of its desync handling. I enabled that on both Win & Linux hosts, ran a match between the machines until they desynced, and diff'd the game's own logs, then confirmed from the Wine logs that the faulty values were coming from CRT-related math functions. It's always fun when you get to use a game's own debug utils to track down a problem.

Anyway it'd be great if the game devs included their own math libraries instead of relying on the OS's. That would fix the problem quite nicely.

Do you know if the code from the blogpost you mentioned is publicly available? I don't think I could find it but I'd love to give it a try

I don't, he did that work after I left the job. You could email Rémi or hop into one of the Wine dev channels to start up a conversation.