RE: Project Zomboid
Interesting that this log that you have seems to have the correct version, 41, but a clean install of the docker container has the masterLog showing its installing 40.43
Using just steamcmd it does look like "app_update 380870 -beta b41multiplayer validate" so in order to use the b41 multiplayer version you need to change the game ID to include the -beta flag.
Using the Game ID as: 380870 -beta b41multiplayer
DOES install 41.60
With this kind of game using beta "codes" like this it might make sense to pull out and add an optional beta flag or a note in the unraid UI for the GAME ID variable.