I am sorry they don't work for you! I don't have any issues with these on my machine. You could try increasing infill. I printed them in PLA (stiffer than ABS for those who don't know.) I am using an auto-adjusting circuit for my FSRs, and they require very little pressure to trigger - not enough for the mounts to flex.
If I find the time, I may try to improve the rigidity of the structure.