Can We Crack These Malapropisms?

Only @Cheeniya can crack now ..

12) Never troubled by five o’clock shadow, Jimmy’s skin was still gibbous and youthful well into his forties.
I have no clue what this is ..

8) Some sailors complained of side effects when shipbuilders began using cortisone as a floor covering.
cordage, cork, some other material, but what?

15) In the stockroom, Alex was a remarkably productive worker, a regular Stalagmite, and his industriousness was rewarded.
Nope

17) Whenever he felt signs of an oncoming cold, Bill stepped into his organ box.
Nope

18) The commencement address began humorously but built to a suitably horticultural peroration.
Nope

21) The Airbnb guests were querulous regarding the cloaca comforter.
Nope

26) Talk turned to depth psychology, but the phrase laminal space never escaped the tip of Kayla’s tongue.
liminal space?

 

Yes, (8) is corticine.

 

How did you even come across such a thing?

I thought "organ box" should be substituted with some kind of winter/woolly shoes or socks, "stepped into ____" like shoes to escape the cold

 

This "gibbous" is puzzling!
"Glowing" fits in the sentence. I initially thought it was a synonym of "supple" , something elastic therefore could not find any decent word that rhymes or hints from "gibbous"