Can We Crack These Malapropisms?

Few puzzling ones ..

14) Hana cherished an inherited Netscape from the Edo period.
15) In the stockroom, Alex was a remarkably productive worker, a regular Stalagmite, and his industriousness was rewarded.
17) Whenever he felt signs of an oncoming cold, Bill stepped into his organ box.
18) The commencement address began humorously but built to a suitably horticultural peroration.
20) Though she was most proficient on guitar, Rosa was also a gifted lutefisk.
21) The Airbnb guests were querulous regarding the cloaca comforter.

(20) may be

Spoiler

flutist

.

 

That's brilliant!

 

Even I don't know but "gibbous" sounds off-key there, or may be I am looking at the wrong location and the offending word is elsewhere.

 

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 , 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?