I did find this Why is my FontFamily "Arial"? but it doesn't go into what to do if there is anything you can do.
I tried modifying the registry which I hate and consider that a hack.
I'm trying to use Helvetica and Helvetica Black in code C# new Font(familyName, emSize, FontStyle, GraphicsUnit)
I do have those fonts installed.
EDIT: I didn't include any code because it's just the new Font method on System.Drawing.
var font = new Font("Helvetica", 10, FontStyle.Regular, GraphicsUnit.Millimeter);
Although Helvetica and Helvetica Black are installed the above method call returns Arial which I believe is because that's what the Registry says to do and if I ask for Helvetica Black it returns Microsoft Sans Serif which the registry says "Helv" so I'm guessing it's picking up on that.
Even if I tell the registry not to do that I'm still getting those values.
The ultimate goal was to display to the user a list of installed fonts and then allow them to pick ones to use.
Something else I just noticed
System.Drawing.FontFamily.Families
Returns 237 fonts but Helvetica and Helvetica Black are not listed.