Someone can correct me if I am wrong but I have NEVER used the plural "desenuri" before nor have I seen this plural form of the word "desen" in my dictionary.( though in the online dictionary it says that desenuri is also possible !? )
I have ALWAYS used desene = whether it was a drawing or an animated tv series
I have found though a research paper of loanword in Romanian which says the following:
" For loanwords: The original gender of nouns is generally retained, and inanimate objects that do not have a gender in their source language usually receive ‘neuter’ gender and morphology, which implies masculine agreement in the singular and feminine agreement in the plural.
Examples are gref ‘grapefruit’ from English grapefruit and pix ‘ballpoint pen’, probably borrowed via English from the brand name Bic, with the respective plural forms grefuri/grefe and pixuri requiring
The reanalysis of borrowed plurals ending in /-s/ as singular forms and the subsequent addition of the plural morpheme /-uri/ is commonly found,especially with loans from English, as in cips (sg.) from English (potato) chips, with the plural cipsuri. "