Your script has a bug (not fatal one that cause the crash but still, I think it's serious) Although, there ARE a lot options so I'm not sure if it's my fault and I missed something.
Version I'm using: Version: 2.0b
I was trying to set it up so I'll only get 3 lines in the message box, not normal four lines. I deceased the message box height so it'll look nice with only three lines, not 3 lines and 1 blank line. I also changed a lot other things (like namebox, face, etc) but it seems like the window height is responsible for the bug.
If I set the window height low, the font type and font size is no longer in effect. I did not use the script syntax to change the window height. I used the config block in the script since I want it to be permanent.
The code is
DEFAULT_WINDOW_HEIGHT = 97 #128 is default
Recently, I decided to test it in Advance Text System demo I downloaded, and changed the font type. It doesn't seem to work at first, but after talking to few NPCs, it finally changes to the font type. (There was introduction speech, then I talked to the green-haired girl. The font didn't change until I talked to the green-haired man after)
I then deceased the height in that demo script, the font type never took effect, not even after I talked same NPCs.
While testing your demo for the bug, I encountered another bug (although I'm not sure if it's because I did not adjust few other options in the block to make it to work)
If I deceased the window height, the scrolling window screws up. It shows first three lines, and nothing after that. It's just bunch of blank lines and I have to press [ENTER] key repeatedly until the window finishes processing "invisible" lines, and end the conversation with the NPC.
It's not important for me because I don't intend to use the scrolling effect in my game. Although you might want to know about it.