Thanks, Peter. Okay, I have tried this but without too much success.
I set up a landscape, two column page and imported the Russian text. That resulted in 13 pages of Russian text, in both left and right columns. I then added the English at the end of the Russian and now have 26 pages in total. Then, as you suggest, I inserted a Column Break after the Russian. This forced the English to begin afresh on page 14.
Now I need to find a way of keeping all the Russian text in the left column of all the 26 pages so that I can have the corresponding English translation adjacent in the right column (for all pages 1 - 26). I have explored your suggestion of Layout Breaks but think I have either misunderstood you, or I am doing something fundamentally wrong!
Okay, so now I need to be a little more specific to help you visualize the problem. On my page 1, left column, I have three paragraphs of Russian. Para 4 begins close to the bottom of the left column and flows, as expected into the right-hand column of page 1. Now, if I insert a Layout Break at the end of para 3, I find paras 1-3 are uniformly shared across both the left and right columns. Para 4 stays in the left column, and understandably has moved up somewhat, but para 5, following correctly below para 4 in the left column now flows into the right column, following on from the end of para 3. There are no visual breaks, so now my page 1 left column reads paras 1, 2, first part of 3, then 4 and first part of 5, while the right column now shows the second part of para 3 and the the second part of para 5. This is confusing to understand and confusing to read. This is no good at all.
Inserting a Section Break after para 3 results in para 4 beginning in the left column of page 2 and the whole of the right column of page 1 remains blank. It also seems that that right column is now rendered inaccessible and so I will not be able to put the English of paras 1- 3 into it so that they are adjacent to the Russian paras 1-3 in the left column of page 1.
Inserting a Page Break instead of a Section Break produces the same effect.
In conclusion, I am still stumped. To keep all the Russian in the left column of all 26 pages, I would need to insert a page break at the end of every page .... but then there would seem to be no way to insert the English into the corresponding right-hand columns, beginning of course on page 1. I am surprised that such a fundamentally useful word-processing facility is so complex (or perhaps impossible) in Pages.
Thanks, again, Peter. I have to say that you have been more helpful and informed than any others that have tussled with me over this difficulty.