Could you please send capsense button FW of below link document(P24 and P25, Figure 2-15. CapSense Buttons Service)?
I found FW of proximity and slider from CY8CKIT-042-BLE sample FW.
But I could not find button FW.
I didn't find a ready-made fw of buttons.
It should be similar with slider.
Refer to other example code of capSense button to get the button status out. Then file the button status in BLE advertisement same with slider example.
May it help you out.