Keynote Tailoring's change notes disappear when you leave the page. Copy them first.
Every tailored keynote comes back with a list of what changed and the context behind it. Neither is saved with the version. Here is what the tool keeps, what it drops, and how to work around it.

You tailor a keynote for healthcare. The new version looks good, and below it sits a short list of what the tool changed. You skim it, think "fine," and move on to the next industry.
The next morning you open the keynote again and the list is gone. The tailored text is still there. The explanation of how it got there is not.
The notes are not part of the saved version
When you run Tailor it, the response carries three things: the tailored description, a list of changes, and a few lines of industry context. Only the description is stored as the version. The other two live in the page's memory for that run, and the code that holds them says so in a comment: they are kept per freshly generated version and are not persisted.
In practice, you see "What changed for Healthcare" and "Context it drew on" right after a run. Reload, close the tab, or come back tomorrow and open the same version from "Your versions," and the panel under the text tells you plainly that the change notes only come back with a fresh run.
That is not a bug to wait out. It is how the tool works today, so plan around it.