Jain tradition remembers two recensions of the canon made at about the same time in different places. Skandila made one at Mathura. Nagarjuna made one at Valabhi in Gujarat. The tradition also remembers that the two did not agree, and that the difference was still unresolved when the final Valabhi redaction under Devarddhigani took place generations later.
What the tradition does not record is what was reconciled, on whose authority, or by what method. The final redaction is presented as a settlement without a description of the settling. That leaves a real hole in the textual history of a canon that a living community treats as scripture, and modern scholarship has not been able to fill it from the manuscripts, which do not preserve variant lineages traceable to one recension or the other.
Standing outside all of this is the Digambara community, which holds that the canon in the Svetambara sense was already irrecoverably lost by this period, that what the Svetambaras redacted cannot be what they claim, and that the true teaching survives in a different body of texts altogether. On that view a council to fix the canon is a council to fix something that was no longer there to fix.
This is not a disagreement about a detail. It goes to whether either community possesses the teaching of Mahavira in the form it claims. The atlas states the two positions and does not choose between them, because choosing would mean ruling on a question internal to a living religion.