I have the same experience in my car, despite recent replacement of the steering wheel. However, I wonder if your focus on the left pad is due to its more frequent use, hence more chances of random faults. Do you use any buttons on the right pad with similar frequency as on the left pad to statistically differentiate their response quality?
In my experience, I use custom button on the right pad for Homelink, which means 2 presses for each time I drive the car, one to leave and one to come back.
I get just as much frustration with Custom/Homelink button on the right pad as I get with DD button on the left pad, i.e. sometimes works perfectly, sometimes requires multiple presses.
BTW, I accept the common belief these devices are like joysticks with added touch sensors, i.e. you must have appropriate amount of finger contact in the middle of the button, not just pressure at the edges, so I pay attention to engage them correctly every time, yet still get random quality of response.