Hi Ouch Mouse Studio,
Yes, Wwise 2019.1.4 does not work on either Catalina or Big Sur.
Instead, download the newest Wwise minor version related to (Wwise 2019.1.11) and use that to open it.
* You don't need to upgrade the integration in WAG as the versions will be compatible. You just need a newer Authoring to run on your MacOS Big Sur.
Let me know if it works!