From disc 3 onward, I put together https://musicbrainz.org/release/57c5fca9-48f9-4840-96f7-3053f2ccbf71 by using the "Add Medium" button, and the "existing medium" option. Then I used the track parser to change the titles to match the booklet, and finally on the recordings tab (when required) used the "re-use" button.
That seems like it should work, but somehow it appears recordings got scrambled. For example, they're right on https://musicbrainz.org/release/62aa07b5-d4cd-39ae-b23a-26838773c60d where I copied disc 3 from (it's disc 3 in both collections).
Trying to figure out where this went wrong—any ideas? All the swapped ones appear to have the same name except for the movement number.
(I've put in edits to fix the mess).