[walthamstow]

> Would an English native understand them?

Depends where in Scotland and how much they've had to drink.

On a serious note, words like ken, bairn, breekies, stramash are not that well understood by English people. But it's unlikely a Scot would use them when talking to an Englishman.

[palata]

Right. But is it then that a Scot would just not use some local words, but still speak in their language?

That's different with Swiss-German. If a Swiss-German person talks to you in German, then they are not talking in their language.

[benj111]

Depends where in England.

Bairn is northern English too.