Limited to speaker crossover networks. Yes or no.
It depends entirely on what capacitors were used in the first place and what capacitors were used with the replacement.
There is no general answer.
There are also other issues, if ESR changes substantially, you may get a difference due to simple changes in ESR, for instance, not due to any "capacitive" part of the system.
The major change that most loudspeaker capacitor upgrades apply usually relates to the simplist thing - their actual capacitance. Most of the original parts were +80 -20, so we don't know what they did for sure without measuring them pretty carefully.
In the case of the Sansui, some of the inductors look pretty skimpy. Iron cores, especially too-small iron cores are a flashing red light.
+80/-20????? Where are you getting these numbers?
That is sometimes the tolerance for a power supply electrolytic where more capacitance (+80) is better.
Most low cost NP electrolytics in speakers are +/-10%.
Some companies have them custom wound to spec.
What company are you referring to that used +80/-20 NP electrolytics?