Basically, by rejuvinating crossovers from vintage speakers, I'm assuming the original designer was correct.
Assuming that original design is correct you should be fine. Replace withing <5% of the specified values and preferably same type and you should be fine. Blindly changing electrolytic capacitors to the film type in vintage speakers with complicated crossovers could lead to "strange consequences" as already mentioned, even (rarely) with just first order filters. So, don't toss old caps at least for a few weeks while listening in case you don't like that new experience
