Canadian perspective here. We also had our troubles with separatism. Back from the 60's till the late 90's Quebec had very good and valid reasons to separate from Canada, mostly because of prejudice against their language and culture. They came very close to separating from Canada in 2 referenda. A few things decreased these tensions: compromise, increased economic dependence, immigration and cultural change within Q…
> very good and valid reasons to separate from Canada, mostly because of prejudice against their language and culture
It's rare to see this acknowledged outside of Quebec, so, thanks.
> increased the use of French within the English speaking part of the country
It's important to note for the comparison that this has been eroded extremely quickly. Supreme court judges don't have to speak French, and the Supreme Court ruled (6-3) two years ago that provinces are not obliged to translate laws into French. The lesson here is don't take things for granted that aren't in the constitution. (I don't know how much language is an issue for Catalonia but I can only assume it's a part of it.)
> The Quebecois culture changed becoming more cosmopolitan and less Catholic (we call it "The Quiet Revolution").
I don't think you meant to misdirect here, but the Quiet Revolution happened in the 60s, and is therefore not a consequence of the modern sovereigntist movements which lead up to the first referendum in 1980.
> After these changes, separatism is today a political liability in Quebec. Their separatist party only succeeds when they disguise their separatism.
It is still an issue, in the sense that some people will vote for the party most "likely" to hold a referendum. In practice, we all know the status quo is too profitable for any powerful party to attempt real change.
It is also important to note that Quebec still very much feels like a different nation, to me at least, and we often diverge strongly on political issues related to culture. See this map from 2011: https://imgur.com/gallery/w3uoK9W
As long as this "two solitudes" phenomenon persists, the separatist movement will continue to exist. It is doubtful to me that there are any concessions on the part of Canada that could bridge this gap, but I'm certain that Spain is different, in that it could effectively have killed the whole affair with simple financial negotiations. In hindsight, the lack of openness to compromise was quite obviously a shortsighted decision.