This does not seem to be possible. You can only download the comparison report during the process, but not
I created a post in the product request some time ago, because it would be really usefull to have the detailed information saved in Anaplan. Now you really need to download the comparison reports and save them offline.
With the proviso that best practice should be to keep revision tags in a separate module, I do have a workaround if you need to copy out the text on the revision tags into a text file of Excel sheet.
You can't copy the text on the revision tags page from the Revision Tags section of the model. However, if you click compare, then you get a pop up window where the text can be selected and copied. This doesn't give you the Created By column or the text from the revision tag which you are using for Compare, but gets you most of the way there. I use the Description field to give a brief narrative on what the revision tag is about and this has been a useful memory jogger for me.