Hi,
I have experience for 15+ years in electronics/embedded development. I have several years of advanced AVR/arduino development, including library development from scratch. Practically all Arduino AVR boards used, like: 2009, 2010, UNO, MEGA, NANO, MICRO, MINI, etc. Several shields used like Ethernet (W5100, ENC28J60, etc.) with various IP protocols implementation, various graphical TFTs with and without touchscreen and various BUS types (parallel, SPI, I2C, etc.), all kinds of sensors and buses, serial and parallel memories, etc.
I didn't get it very well from your project description, but I guess you have several capacitive touch "switches" connected to arduino inputs that are working correctly individually, but not all at the same time ?
I think you probably have a problem of a "blocking code" implementation, that when each capacitive input is being sampled, all the others are not being sampled, and then delays happen and touches are missed.
If this is the case, what would need to be done, is to re-implement you sampling code to work in a non-blocking implementation. I have already done this kind of "optimization" countless times in the past, and think I can help you in your project.
If you are interested in my bid, please let me know some more details about your project and I'll be able to answer you back telling if I'm up to the task or not. Feel free to contact me.
Regards,
Carlos.