It seems that both .rw3 and .rwsw files come from a tool called RapidWeaver, which is a web design tool for Mac. We have not found any particular mentions of rw2 to rwsw conversion or what it might be, except the fact that both are used in the app.
Perhaps it is related to import of previously made designs back to the tool and saving them as the default project files and if this is even doable, it will be only with the original software.
Updated: November 6, 2023