I read in the handbook that the nominal input voltage of the Reform was 24V, but that it will accept 9-32V of DC power.
I have a very basic understanding of electronics, so I’m not really sure what it means.
If I charge the laptop with a voltage different than 24V (but in 9-32 range), will it slowly damage the laptop over time, or will it just lead to a minor loss of efficiency energy-wise?
Can I, for example, regularly use a 19V charger with my reform?
19V should be fine. Optimally your power supply should be able to handle 60W (i.e. ~3.2A).
For any that might be reading this later, I just wanted to add that the Reform’s charging circuitry will take an input voltage of 9-32V, but as @mntmn mentioned above, that source should be able to output 60 watts of power. You get watts by multiplying your output voltage by your amps.
So at 9 volts you would need ~ 6.7 amps to be able to charge the batteries. In general, it is pretty uncommon to find an adapter that outputs so many amps at such a low voltage.
Still this is a nice flexibility!!!