If you need to reduce SPL in a passive crossover you need a L-Pad.
One resistor in line, one across the + and -.

There are on line calculators to allow you to put the dB reduction you want and get the resistor values out.

Something like this

troester.org/ls/lpad.html

Other than that, wrong Capacitor values could make the volume seem louder as one driver could be covering more frequency range than it should.

Modern quality polypropylene caps last pretty much for ever.
Janzen Cross Caps are fine.

I still use passives on the upper two channels of my 5 way system.
I even spool my own inductors. Can get just the right values then.

The signal has been though DSP for volume and time delay and the odd PEQ filter as needed of course😉

I tweak them at times, esp after a big system change, like recently.

The whole system is active though since 2013, so I have no need of L-Pads.
I found, even using high quality film resistors, things sounded better active / no resistors.