In the past, I kept the product name alphanumeric, but used the Bundle display name in the Info.plist file to use extra / different characters.
I encountered a similar problem some time ago with the + symbol - I could not sign any applications with a symbol in the package name. So, I changed the name from Xxx + to XxxPlus and set the Bundle display name to Xxx +. Looks like I wanted it to be in the GUI and the signature worked fine.
source share