C2, C3, C4, C1, C5

C2 and C3 are actually equal importance, being series capacitors. These pass the signal to the tweeter. C4 is a shunt filter cap, and it's important because it ultimately affects midwoofer response. C1 is a bypass capacitor, and only provides a tiny bit of signal at the extreme HF. C5 is part of the Zobel, which sets the load for the midwoofer crossover. This part has a very large tolerance, but if it's way off, upper midrange response is adversely affected.