how do you access attributes of a smartsheet cell object?

I’m not very familiar with Python or with the Smartsheet Python SDK — but could your problems be caused by the fact that you’re using invalid Cell property names in your code?

Seems like the integration tests (for rows) within the SDK repo in GitHub shows how to reference Cell properties when using the Python SDK. For example, I see this code there (lines 105-108)

for row in sheetb.rows:
    ids.append(row.id)
    for cell in row.cells:
        column_ids.append(cell.column_id)

Comparing that code with the code you’ve posted in your question above, one thing that jumps out at me is that you’re using cell.columnId whereas the integration test uses cell.column_id. Likewise, I suspect that where you’re using cell.displayValue — it should instead be cell.display_value. (See the definition for the Cell object in the SDK for a complete list of all property names in the Cell object.)