To modify the direction of the servo motor, chage the linemap(scale.get_units(), 0, 8, 180, 15). Simply flip the last two arguements, so instead of going from 180 degrees (left) to 15 degrees (right), it goes the other way around. Now just cut out some paper and make a creative looking gauge!
Switching either of these wires will make the strain gauge read negative values. This is because the strain gauge acts as a voltage divider. By switching the pairs of wires, the HX711 reads a negative voltage, which correlates to a negative strain being applied to the strain gauge.
By using a bigger calibration factor, the gauge will become more sensitive. Similarly, using a smaller value will make the gauge less sensitive.
To see this solution, download the "I Give Up" file above.