After slightly over a week, my laptop is back from warranty service.
In the intervening time, I’ve gotten autosave working on Composer, hugo, lure, and drascula engines, and made a few changes to how autosave works in agi, kyra, queen, and scumm, so that automated saves now use a special reserved slot with a special filename so that no manually created save will ever be overwritten by an autosave.
As my laptop is back, tomorrow I will be returning to the sword25 save portability problem.