We need to improve our docs to make a few things more clear:

• Schemas do not behave like MongoDB projections, and do not support dotted notation.
• The workaround to this requires all of the nested documents to either not use any of the same names for itself, or the same types as in the parent table, or documents must be flattened using projections or agg pipelines.

Implementation of a solution to this problem past documenting this quirk has been deferred to ARROW-149