@DanH One quick solution/learning process I can tell you....
Load the project (HISE Standalone.sln or HISE Standalone.xcodeproj) >
For MS VS
Search for SampleDisplayComponent.cpp
Here you will find GLOBAL_BOLD_FONT right click Go to Definition (F12)
You will get Font Name.
Alternatively you can open Macros.h and search here.
One more thing you can do (I guess it may work)
\HISE-scriptnode\hi_core\hi_images\ here you will get the font you are looking for.