I didn't read that title but understood story background from some reviews.
But not so hard for understanding first that 糸(ito) means "line(s)" for control.
So that contol sounds are "bond" as "buddy" for their works.
(machine girl "Kukuri" is not a human, "she has same mind like human?")
Karakuri means "gimmick" just moving system in this case as a machine/robot.
(In that story seems "puppet" and "automaton/automatic robot" both type exist)
Very famous Japanese Ninja story title NARUTO's charactor "Kankurou","Chiyo-baa"
also enemy "Sasori" are all "kugutsu(larger puppet) master" very close as gimmick.
https://en.wikipedia.org/wiki/Narutohttp://naruto.wikia.com/wiki/Kankur%C5%8D(kugutsu has not their mind like a human)
But maybe that is not all about charactors relationship background.
In Japan same "Philosophy" stories of manga/anime a lot from over 50 years before.
(Human and Robo, Robo with a mind like human as partner/friend)
https://en.wikipedia.org/wiki/Astro_Boyhttps://en.wikipedia.org/wiki/Tetsujin_28-gohttps://en.wikipedia.org/wiki/Babel_IIhttps://en.wikipedia.org/wiki/Cyborg_009https://en.wikipedia.org/wiki/Tatsunoko_Productionhttps://en.wikipedia.org/wiki/Galaxy_Express_999https://en.wikipedia.org/wiki/Doraemonhttp://cartoonresearch.com/index.php/dr-slump-and-arale/https://en.wikipedia.org/wiki/Kiteretsu_Daihyakkahttps://en.wikipedia.org/wiki/Ghost_in_the_Shell_2:_Innocencehttps://en.wikipedia.org/wiki/Space_Dandyhttps://en.wikipedia.org/wiki/Unbreakable_Machine-Dollhttps://en.wikipedia.org/wiki/Pandora_in_the_Crimson_Shell:_Ghost_UrnBasically Japanese are not thinking "robot is not so far" against our real life from kids.
You already know well Japan was growing up by new techs after WWU(1945),
So Japanese always respect our techs also depelopers in any era.
However would like to mention two more different basic background, first is "buddy story".
History of buddy stories tons of exist more more older era also not only in Japan.
Already mentioned "Robot is not just a machine" for Japanese,
this custom coming from Samurai spirits as "devotion/loyal" for Shogun and their home town(called "country") .
Later era "Momotaro(with wild animals)" also "Hachiko(smart dog)" stories are very famous.
https://en.wikipedia.org/w/index.php?title=Momotar%C5%8D&oldid=7666871...https://en.wikipedia.org/w/index.php?title=Hachik%C5%8D&oldid=76670427...So human with animals style is still continued and to the future,too.
(they cannot speak human lang but they able to do reactions against our requests/calling)
Robots(with mind) are closer than smart animals,
especially we feel a sense of familiarity for "real human style" ones.
(for cute/萌え:moe one would like to "love romance" plus as story)
Last one is "in Japan is not only one God" like "Jesus".
This is coming from "Shinto"culture.
https://en.wikipedia.org/wiki/ShintoSo, Robot also one of human's "tool" but long partner one will be "human-like".
The practice/sense of values of believing in the existence of spirits in long-lived articles/living things
and "having a feeling of reverence/awe" for them was common in Japan,
and the philosophy of Tsukumogami is the same with that of contemporary and ancient Shinto.Most famous line "The ball is my friend" in Captain Tsubasa is easiest for understanding.
https://en.wikipedia.org/wiki/Captain_TsubasaNow "Personification/Anthropomorphism" charactors a lot you have seen.
(Too much titles cannot listed instantly)
So any sounds will be "voice" as somthing of "living".
Also that "機" means not just a mindless machine.
https://en.wiktionary.org/w/index.php?title=%E6%A9%9F&oldid=42391438機 doesn't read "karakuri" Japanese lang class in school, author's "gimmick" :)
