In HITMAN 2, it is possible to get all WEMM (mirrored MMEW) container files. However, this tool does find some .WWEV files where it is possible to collect some SFX sounds. But they do not include all existing audio data.
I also noticed that these files have similar problems like the TXET and ENIL files with no bytes.
When I was extracting HITMAN and HITMAN 2, the .WWEM files were extracted by a BMS script for HITMAN 2016. Maybe they have encrypted the wwem sound data in HITMAN 3?