The bug you found tells there is no bug, except in the doc, and this has been fixed as it tells that textFont is supported.
But apparently it doesn't work with default font: you have to define the default font yourself.
I did a test, using createFont as it is simpler for me, but it should work with loadFont as well:

1. PFont font1;
2.  
3. void setup()
4. {
5.   size(300, 300);
6.   font1 = createFont("Broadway BT", 48);
7.   // Define default font
8.   PFont font2 = createFont("Art Deco SSi", 96);
9.   textFont(font2);
10. }
11.  
12. void draw()
13. {
14.   background(120);
15.   pushStyle();
16.   textAlign(CENTER, TOP);
17.   fill(80);
18.   textFont(font1);
19.   text("abcdefg", width/2, 10);
20.   //hint(ENABLE_NATIVE_FONTS);
21.   popStyle();
22.  
23.   text("hijklmn", 50, 150);
24. }