This isn't a full review, but I glanced through and I noticed a minor typo:
+debian/brllty-usb-generic.rules ... + cp /usr/share/doc/brltty/examples/brllty-usb-generic.rules /etc/udev/rules.d/86-brltty-usbgeneric.rules
It's brllty vs. brltty. Since it's in two places the code will presumably work, but it might be worth fixing now to avoid confusion later.
This isn't a full review, but I glanced through and I noticed a minor typo:
+debian/ brllty- usb-generic. rules doc/brltty/ examples/ brllty- usb-generic. rules /etc/udev/ rules.d/ 86-brltty- usbgeneric. rules
...
+ cp /usr/share/
It's brllty vs. brltty. Since it's in two places the code will presumably work, but it might be worth fixing now to avoid confusion later.