To install mingw-w64-wine-gecko, run the following command in macOS terminal (Applications->Utilities->Terminal)
sudo port install mingw-w64-wine-gecko
To see what files were installed by mingw-w64-wine-gecko, run:
port contents mingw-w64-wine-gecko
To later upgrade mingw-w64-wine-gecko, run:
sudo port selfupdate && sudo port upgrade mingw-w64-wine-gecko
Reporting an issue on MacPorts Trac
The MacPorts Project uses a system called Trac to file tickets to report bugs and enhancement requests.
Though anyone may search Trac for tickets, you must have a GitHub account in order to login to Trac to create tickets.