Hi, Alessio! Welcome to Escova.

It's totally reasonable for a bunch of merchants to relocate to Escova and continue their business there due to conflict on the Mainland, so long as they're able to continue having access to what they usually sell or start with new wares in Escova. They would probably be most successful if they previously had connections on the islands or if they continue to have connections on the Mainland that can get them Mainland goods to sell on the islands.
Opinions of refugees vary, so it's tough to say how well-off/middle class merchants would be treated by any social class without generalization. Typically citizens of lower classes probably tend to be more tolerant of refugees whereas the wealthier citizens would be less interested in tolerating them. However, refugees and Mainlanders have a more significant impact on the middle class citizens, causing the refugee quarter to expand into their residential areas and competing for their jobs/resources. So, while nobles and the wealthy might look down on refugees for being dirty or foreign or just generally
not one of them, some of the middle class citizens may take a more serious issue with them because of how refugees are impacting their daily lives. With all that said, it
is important to note that not all citizens are bothered by refugees or will treat them like a problem.
Bottom line: Merchants from the Mainland can definitely start up business in Escova, but there will be challenges due to some prejudice, and it's important to consider where the things they're selling are coming from.
If you have any more questions, feel free to toss 'em at us!