I'm no lawyer, but i am 99% sure the very short answer to your question is "no".
The legally admissible boundaries are recorded in the cadastral record which you can obtained from city hall. That record is generated by surveyors who do the similar process to what you describe (start at an origin, draw lines at certain angles etc) but with real life measurements.
Any software generated boundaries will be prone to different types of errors which will make them inadmissible. Courts like dealing in absolutes. There exists a reliable method of doing this, and its how they generate the cadastral record.
Even with highly accurate lidar or remote sensing images, when it comes time to plot out the property in real life, the process requires professional surveyors who will then sign off on the results.
Is there some way to estimate the maximum error in real world distances of such lines as shown on the map from their actual location?
You would have to draw the polygon in your software, get some coordinates from the software (the corners of the lot for example), and then go to the property and measure the real boundaries with a high accuracy GPS device ($$$) and then compare the two sets of readings. Doing this for one property would give you an idea of the margin of error of the process, doing it for multiple properties will help you dial in the margin of error. That would be the process you are asking about in this above quote... but it still wont be admissible.
You could compare those results to the cadastral files to guage the margin of error, but once you have the cadastral file i'm not sure i see the point of making another record/file.
the context might greatly change what is admissible. Trying to move a boundary between two houses is very different than say, trying to estimate the surface area of a very large property.