Open questions
One question, and what would settle it.
Is the thirty-five letter painti order attested in the Punjab before the sixteenth century, and if so in what form?
Why it is open. Sikh tradition credits Guru Angad with the script, while historians of Indic writing hold that the letterforms were already in mercantile use in the Landa hands. Both accounts are argued from the same thin evidence, and the atlas records the disagreement rather than settling it. What neither account establishes for this pass is whether the specific ordering of the thirty-five, including the placement of Sassa and Haha ahead of the five series, predates the Gurus or was fixed by them.
What would resolve it. Dated Landa or proto-Gurmukhi material with an explicit letter sequence, whether a scribal exercise, an account book heading or an inscription, from before the middle of the sixteenth century. A published palaeographic study of the ordering itself, as distinct from the letterforms, would also close it.
Field. Indic palaeography and the history of writing in the Punjab