Well, this example is quite curious. Catalan is understood and used by most of the people who live in Catalan speaking regions, but it isn't the first language of most of the people who live there. Pretty much the 95% are bilingual (Catalan and Spanish). In fact, more people speak Spanish as their mother tongue than Catalan but they switch between them when required.

Maybe the Scots situation is similar, people learn and use both languages and change to the one they feel most comfortable with.