This behaviour is a fundamental consequence of the order in which a page is processed when it is stored: first the wiki text is parsed and expanded, second the text and extracted data (information for "what links here", categories, SMW data) is stored. So the result of the query is computed before the data is stored. I do not see how we can change this in a practically feasible way. The current behaviour is certainly not a deliberate design choice for helping people to compare old values; we really have no idea how to do it differently.

Regarding the "cached" option, I note that SMW does not store a history of its data. So there is only a single copy of the data in the data base at any time, and we cannot provide an option for selecting another older version.

I understand. So perhaps you could add something that the page won't end up in the cache or use the job queue after saving the article so that the first person who will enter the page will trigger an purge automatically.
Only the editor would see the wrong datas in this scenario. But perhaps this will already need to much performance on big wikis and it won't be anything else than processing the page two times in a row...