I recently came across an interesting article (in Romansh) about some Romansh words deriving from a Latin nominative.
As with most modern Romance languages, Romansh words generally derive from old Latin accusative forms (this also explains, for example, the plural ending -s in languages such as Spanish, French, and Romansh).
However, Romansh kept at least some case distinctions for a while, and there are now a couple of doublets that derive from nominative/accusative of the same word.
The article cites the following pairs: Dieus/Deus/Dius/Dös/Deis/Des < DÉUS vs. Diu/Deu/Dieu/Dia/Di < DÉUM; Segner/Signer (now predominantly in reference to God) < SÉNIOR vs. Signur/Signour (now the general word) < SENIÓREM; paster/pester < PÁSTOR vs. pastur/pastour < PASTÓREM (typically with slight differences in meaning; details depend on the region).
I also remember reading that Romansh must have had at least two cases at the time many town names were borrowed into German — leading to the interesting situation that the borrowed name preserves an older form of the language. Specifically, there are a number of German names of towns that end in -s (which used to mark the nominative case for those words) while the modern Romansh name no longer has that ending.
I don’t remember which towns they referred to, but looking at a list of towns in Graubünden in the German Wikipedia, it may have included some or all of Flims/Flem, Rhäzüns/Razén, Rodels/Roten, Schiers/Aschera, Sils im Engadin/Segl, and Tomils/Tumegl.
All that made me wonder whether to include something similar in Engadinese — that is, to have most modern words derive from the Greek accusative case but to have some vestiges of the nominative case, either in specific doublets (perhaps related to religion, since that may preserve archaicising language?) or in town names borrowed into, say, Rhaetian.
Borrowing the accusative in order to get a plural in -s seems not so necessary if you start from Greek rather than Latin, since Greek has both nominative and accusative in -s in the third declension, but then, it’s similar in Latin with III, IV, V. And in first and second declension nouns, you only have -s in the accusative plural. So accusative seems a good way to go if you want something similar to what happened in the Romance world.