It's a toggle command, so the keys may not differ if in translated address (though the binary I'm sure is different). My brightness keys have the same address, though they were different. There is nothing for you to fix there.
This is a proprietary keyboard, meaning the drivers must be used in order to access the key combos that you are using.
Search your specific model, bottom of the computer in the big sticker, and Ubuntu 20. Maybe add keyboard function keys.
Though the acpi scripts were installed by default, you may need a newer version of them, which is why we recommended installing acpi support, as this may resolve the issue.
Installing a newer kernel could possibly as well, since the newer kernels include support for newer hardware, even proprietary (Asus is a popular brand that will have coverage in newer kernels).
This isn't an overnight, download and you're done issue. I know, i went through it. It took me weeks to find the scripts, properly install them and ensure functionality. A few months later i went from Zorin 15 to 16, and all of it was included... scripts unnecessary (it was a clean install on a freshly formatted drive).
Since we don't have your exact model and this will be a matter of trial and error, each recommendation will have to be explored, by you, to attempt to resolve this.
As volume and mic controls are on the taskbar and in settings, it is not like you are without control. They are convenience shortcuts, nothing more.
I'm sorry, but suggestions and direction are the best we can do to assist you to resolve it. Try the acpi command. Try a newer kernel (there are tutorials in the tutorials & guides category to install newer kernels).