Yaqṭīn as substratum vocabulary?

A strong contender for the most obviously ridiculous etymology in Jeffery's The Foreign Vocabulary of The Quran is his attempt to derive yaqṭīn "gourd" from a "garbled form" of Hebrew qîqāyôn (p. 309). Is it possible to do better?

Like ḍarīʕ, yaqṭīn is barely attested in early Islamic-era literature apart from Qur'ānic allusions and botanical texts. However, in this case the grammarians also take an interest, due to the word's slightly unusual form. Sībawayh (d. 796) notes it as one of two nouns of the form yaCCīC(the similar pattern yaCCūC, mainly for animal names, is more productive), along with a yellow-flowered desert plant called yaʕḍīd (Launaea mucronata). The latter word is well-attested in modern Arabic dialects, eg Najdi ʕaḍīd - and has passed into Korandje, the Songhay language of an oasis in southwestern Algeria, as yaʕḍud; I first heard it there, in a chant from a children's story:

aɣ a išən kadda, I'm a little goat,
aɣ a nɣa tantərama, I eat tantərama,
aɣ a nɣa lyaʕḍud, I eat Launaea.

Now, yaʕḍīd is presumably derived from the root ʕḍd, "support" (etc.); despite its scrawniness, the plant holds itself well above the ground. A Hebrew or Aramaic origin is obviously out of the question, given the ḍ. Ibn Durayd (d. 933) cites a third word of this form whose origin is clearer: yaʕqīd "thickened (crystallized?) honey", related to 'aʕqada "thicken (a liquid)" (ويَعْقيد: عسل يُعقد حتى يَخْثُر). By analogy, one would expect yaqṭīn to be derived from the root qṭn, and this is exactly what al-Zamakhsharī (d. 1144) not unreasonably proposes:

واليقطين: كل ما ينسدح على وجه الأرض ولا يقوم على ساق كشجر البطيخ والقثاء والحنظل، وهو يفعيل من قطن بالمكان إذا قام به. وقيل هو: الدباء.
Yaqṭīn is anything that sprawls on the surface of the earth and does not stand on a stalk, like the melon and the snake cucumber and the colocynth. It is (of the form) yaCCīC, from qṭn, "it dwells/settles" in a place if it comes up there. It is also said to be the gourd.

However, the fact that Arabic has only three words of this form - two of them plant names, and one related to honey extraction - should arouse our suspicions. If a language has a small class of morphologically anomalous nouns all relating to wild food-gathering activities, the hypothesis that should immediately spring to mind is: this is substratum vocabulary. In other words, these three words - especially yaqṭīn and yaʕḍīd - should be suspected of being borrowings, not from some garbled Hebrew source, but from the indigenous Semitic languages spoken in the Arabian peninsula before the spread of Arabic. If so, Western Qur'ān studies' excessive focus on written sources seems more likely to obscure linguistic history than to reveal it.

(Yes, you didn't misread that - epigraphic evidence suggests that Arabic expanded from northwestern Arabia into the rest of the peninsula within historic times. Ahmad Al-Jallad has been doing some interesting work on this issue, summarized briefly on this Twitter thread.)