I help out with Vuo support and I'm part of the think-tank called "Team Vuo." Depending on our present needs, some of my work can be writing about and sharing the Vuo story. We believe there are all kinds of people who will embrace Vuo once they discover it’s out there!
Yes, it is possible to limit the text field length if you use Receive Keyboard Typing in conjunction with Make Text Field. The downside is that this configuration is less flexible than Make Text Field by itself when you are making changes. I'm sure there are several ways to do this, but the attached composition makes the most sense to me.
When making changes, this composition works correctly only by backspacing (deleting) from the end of the entered text field.