Soll das Schottisch sein?

I checked the DSL and it has no entry for an adjective "snick". It has "snick" as a spelling variant of "sneck":

None of what is describe there seems to fit the OP's context.

Master Tootie then lived in Mauchline; a dealer in Cows. It was his common practice to cut the nicks or markings from the horns of cattle, to disguise their age. He was an artful trick-contriving character; hence he is called a Snick-drawer. In the poet's "Address to the Deil" he styles that personage an auld, snick-drawing dog!

(snick/sneck=nick, Deil=Devil)

From this "snick as the devil" makes sense, and the "young gunnie" is being similarly deceptive. #6 refers to the overhead beams being scrubbed clean, removing the signs of age similarly to what the original snick-drawer did. I leave the German translation to native speakers.