That's not a safe assumption to make. English has borrowed quite a bit of vocabulary from Dutch, either directly (keep in mind the longstanding presence of Dutch merchants in the south of England) or through French. Rabbit seems to be one of the latter given the existence of French dialect forms such as rabbotte and robète.

Middle Dutch robbe (Mod. Dutch rob) can mean both "rabbit" and "seal". In Low Saxon and Standard German, Robbe only applies to the latter (their words for "rabbit" being, as mentioned above, descendants of cuniculus). Kluge speculates that it's connected to an extinct word for "brush", applied to both rabbits and seals on account of the appearance of their whiskered snouts. The ultimate etymon seems to be the source of the verb rub (cf. Norwegian rubba, Danish rubbe, both meaning "to scrub" or "to scrape").

Cruche - crusca ?

Except the form one would expect then is *crúiste. That doesn't exist, but crúisce is found in Middle Irish. eDIL suggests the origin is "(Engl. cruse infl. by uisce ?)". Cruse "a small earthen vessel for liquids; a pot, jar, or bottle" [OED] is a word of uncertain origins, though it has cognates elsewhere in West Germanic.

My suggestion is back formation: the diminutive of crúisce would be crúiscín, which is quite well attested. Say you knew only crúiscín and wanted to get from there to the root form. Well, if you took bosca/boiscín as your model rather than ciste/cistín, you'd produce crúsca rather than returning to the original crúisce. The fact that crúsca doesn't seem to be attested before the modern period provides support for this conjecture.

In a review in a journal of the Dialect Atlas (volume 2) there is mention of the Irish of Kilmovee (point 62) in Mayo, that acted as a 'focal point' from where radiated out a form of final stress, but differed from Munster in that a) stress shifted to initial position either freely or in specific environments, b) -ach(t) is not stressed like Munster, c) bi-syllables where there is a long final consonant ('capall', 'gorm', 'fearthainn' etc)

http://www.jstor.org/stable/20495871?se ... b_contents

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The surname Cusack is originally French from the surname Cussac. Ironically there are more Cusacks in Ireland than there are Cussacs in France.

Here are some more -
searabanc, cadastrúil, caidre, baitist, beaignit, astraláib, caife, caraf, caramal, cairbínire, bagaitéal, carabú, barún, carnabhal, casaról, (dath) béis,, ceintilítre, ceintiméadar, ceintigram, cláiréad, asplanád, fiúsailéir, (gouache) - guais, naoisil, pabhán, portmanta, sabaitéir, tabló, tointín......