If company declared dividend on date X, and then updated Ex-Div date on date Y I want to be able to see the un-updated data if I query as of date X. Is that possible?
You question boils down to whether in the dividend history records Refinitiv treats this as a single dividend event or as two dividend events: one dividend that was rescinded and another that was paid. I'm afraid the moderators on this forum do not have deep content expertise in every type of content available through Refinitiv products to be able to answer your question. The best resource for content questions is Refinitiv Helpdesk, which you can reach by calling the Helpdesk number in your country or by using Contact Us capability in your Eikon application.
I do not fully understand the question here.
I would suggest that you contact the Refinitiv Content Helpdesk(at https://my.refinitiv.com/) to try to retrieve the information you are looking for on Eikon Excel with =TR function.
Then you can replicate that on the Eikon Data API(Python) using the same identifiers and fields..