This is probably the last post for this thread: MKVToolNix 99.0 is released, including macOS binaries (arm64, x86_64 and universal).
The Homebrew cask will support updating to the new release as soon as the changes are verified by their team (they’re usually pretty quick, try again tomorrow if it’s not ready yet).
This is intended to be the pattern as new versions of MKVToolNix are released, in other words this should now be ‘business as usual’ 
Onward!