Refactor comparing length of dictionary mapping string keys (e.g. "position")

[bobleesj]

The changes in the PR were implemented to ensure compatibility with Python 3.12. However, the code was deemed brittle, so refactoring should be considered.

Originally posted by @sbillinge in #137 (comment)

[sbillinge]

closed as either fixed or not needed (review of code shows that it is a strict test and what we want)