Once Lucerne fell, so too would the rest of central Switzerland, and 2/3rds of the Sonderbund. If you want a Catholic victory, you'll need to find a way to prevent this.
I'm not entirely sure how the Sonderbund could pull out a win, however. The Federals outnumber and outgun them in every category. Add in an unwillingness to actually fight among both sides as OTL, and it's doubtful the war will last longer than a few months.
Anyways, asumming a Sonderbund victory, you'd see Switzerland return to a decentralized Confederate model with an emphasis on rural identity. This would result in a much more unstable and poorer Switzerland overall, as the centralization of Switzerland into a federal state was critical in setting up the institutions that would propel it to prominence in the 20th century.