Linguistics can tell us what makes the poem incoherent, how the "speaker" is multiple, but not who the speaker is.
Both monolingual and bilingual French dictionaries can be found online, such as the monolingual Lexilogos or the bilingual French Linguistics dictionary that switches from French to English or from English to French.
Clinical Linguistics and Phonetics 18, no. 4-5 (June-August 2004): 235-57.
French Linguistics offers a decent online dictionary that can translate either from English to French or from French to English.
Resources for Tolkien Linguistics - This is an academic site that has devotedly explored the nuances of Tolkien's languages.
J.R.R. Tolkien's fascination with linguistics and lore led to the development of multiple Lord of the Rings languages.
Clinical Linguistics and Phonetics 18, no. 4-5 (June-August 2004): 341-55.