You can link alternate frames as in the attached linked frames.odt file.
linked frames.odt
Select the first frame to get the handles - this brings up the Frames Toolbar. Click the link (chain) icon and click the second frame to establish the link. It shows as a line when a frame is selected. IT works across page breaks.
I would not do so for any document longer than a few pages because of the difficulty in keeping the pages aligned as the text was edited.
My preference would be one document for each language and forget about accurate page splits while writing. When the translation is completely finished and fully proof read and you can guarantee there will be no more changes, set the page breaks to align the original and the translation. Now copy and paste pages to give the alternate pages you want.
If you are publishing as a PDF you could use PDFSAM to split the two documents into separate pages and then merge the pages in order. You would have to force the page numbering in each document.to be 1 - 3 - 5 and 2 - 4 - 6 for actual pages 1 - 2 - 3 but that is simple.
If this helps then please tick the answer and/or show you like it with an uptick.
Check Help - AOO Help says
To Link Text Frames
You can link Writer text frames so that their contents automatically flow from one frame to another.
- Click the edge of a frame that you want to link. Selection handles appear on the edges of the frame.
- On the Frame bar, click the Link Frames icon .
- Click the frame that you want to link to.
You can only link frames if:
The target frame is empty.
The target frame is not linked to another frame.
The source and the target frames are in the same section. For example, you cannot link a header frame to a footer frame.
The source frame does not have a next link.
The target or the source frame are not contained in each other.
When you select a linked frame, a line is displayed that connects the linked frames.