Can replacing a capacitor with a different brand cause audio channel imbalance?
Such a high-value capacitor can find two usage areas in a MoBo's audio subcircuit:

Bypass capacitor for the audio codec chip's ADC or DAC supply.
Coupling capacitor for Line Out channels -- for better bass response.

Regarding your problem, most likely the 100uF capacitor that you have replaced was a coupling capacitor. Some old motherboard designs have 100uF coupling caps along with a low-value (e.g. 75R) series resistor, for both left and right channel line outputs.
The capacitor you used as a replacement has the same size, same capacitance but x5 rated voltage. This may tell us the original one has very low ESR and show very low impedance at audio frequencies compared to the other. So this may lead to some audible imbalance between the channels. So you should either replace the broken with the original one or replace the other original one (because there should be another 100uF) with the cheaper one.
The &quot;audio-grade&quot; thing is almost always a marketing hype, but I should say that some good quality electrolytic capacitors perform better (e.g. degrade less) in audio frequencies and even high-temperature environments.