The word Erce appears in this text and, so far as anything surviving shows, nowhere else. It is addressed, it is called the mother of earth, and it stands in the position a name would occupy. That is the entirety of the evidence.
Everything beyond it is proposal. Erce has been read as the name of a goddess otherwise lost, as a title rather than a name, as a borrowing from another language, as a corrupted form of something else, and as an exclamatory particle that is not a name at all. None of these has become the accepted answer, and the reason is not that scholars are divided into camps defending rival solutions. It is that there is nothing to test a solution against. A single occurrence of a word cannot establish its meaning, and no second occurrence has been found.
The atlas therefore records the identity of Erce as unknown rather than debated, which is a real distinction in this schema: debated means the argument is live and readable, and unknown means the work was begun and could not be concluded. What would change the position is a second attestation, in a charm, a gloss, a place name or a personal name, that shows the word in another context. Old English glossaries and the corpus of English place names have been searched, and continuing that search against material catalogued since is the concrete task.
The larger question the charm poses, whether it is a Christianised survival of pre-Christian agricultural practice or a Christian composition using the language of the land, is a different one, and that one is genuinely debated.