Is there anyway to compile JUCE 8 on Mojave? Xcode 10.3…
“The macOS 11.1 SDK (Xcode 12.4+) is required to build JUCE apps. You can create apps that run on macOS 10.11+ by changing the deployment target.”"
No, you’ll need to use macOS 10.15.4 and Xcode 12.4 to build JUCE 8. I think most devices that support Mojave also support Catalina but you will need at least 4GB of RAM I believe.
Thanks. Sadly, my 2012 Mac Pro 12-core cannot run Catalina; Mojave is the last version for that machine. 
I knew this day was coming…
I haven’t used it and I’m not recommending this but if you feel inclined to look into it more there is the macOS Catalina Patcher which claims to allow Catalina to run on older devices. However, if you experience issues isolated to just using that patcher it’s highly unlikely we would invest any time into investigating and fixing the issue.
There is also one called OpenCore Legacy Patcher. I have seen some positive comments on a forum. Haven’t used it before & Not sure whether it will work for JUCE.