I did not know that mcp3208 is analog to digital, shame .
For tle5010/11 "cs" you mean any pin on pro micro that can be used for internal/external axis?
The case is that TLE501x have internal ADC converter (16? bits), so don't need be plugged in another ADC converter (MPC3208).
You use MPC3208 to send pot' signal for Arduino in digital format, useful if use long cables, or due PRO Micro pin restriction need use more axis inputs than the six ADC pins available in PRO Micro, as MPC3208 has 8 analog inputs.
TLE501x "CS" is the "axis" output and need goes for one of six ADC (axis) input available in PRO Micro. This require individual pin for each sensor.
Curiosity: Why your X-36 stick has 4 axis? Is X, Y, twist rudder and the 4rt?
.
