Quick update -- found a good solution while browsing the source code. The essential clue was in
https://github.com/koreader/koreader...readerlink.lua:
swipe_to_jump_to_latest_bookmark and
swipe_to_go_back. These are in the menu: Gear / links / {Swipe to go back, Swipe to jump to latest bookmark}. Also see comments by @poire-z in
https://github.com/koreader/koreader/issues/3654
With both options enabled, I can easily jump to the references section and back to the body text.
Another KOReader happy customer!