Can we somehow determine the position of the last-page in XSL-FO? If I want to place my footer only on the last page, then how it could be done? As Input data varies and is not
This is how you could define the last page. I don`t know your structure but you can add this in a block and reference with your footer.
<fo:block id="LASTPAGE"></fo:block>
Hope, it's not too late. But anyway, for all interested people:
Create a page master
<fo:simple-page-master master-name="my-last-page">...</fo:simple-page-master>
and put your footer as a "region-after" into that master.
Add this to your repeatable-page-master-alternatives
<fo:conditional-page-master-reference page-position="last" master-reference="my-last-page"/>