Just gave it another try, this time using Bookmarks Sorter ver. 2.1, from the Chrome Web Store -- which should have been installable and usable thanks to the "Install Chrome Extensions" extension for Opera. I did not invoke Bookmarks itself, which remained available for callup in the Sidebar. Right clicked on Bookmarks Sorter under Extensions, which opened a checkbox panel. Left the Speed Dial unchecked, as I did not want to affect that. (It was tremendously briefer -- under 30 entries -- and can be rearranged easily enough by dragging entries wherever I wanted them onscreen, via the mouse pointer.) The Bookmarks Sorter extension seems to have ignored the Bookmarks Bar bookmarks proper, which remained alphabetized from the accident, despite the box for sorting it having been checked. I think the extension may have succeeded in restoring "Other Bookmarks" (which is HUGE, and the largest section) back to By Last Date Entered. If so, guess I would settle for that. Will have to compare to the pre-accident Bookmarks file to be sure of this. By this point, I think the entire Bookmarks file must exceed something like 7.5 MB in size. Can't even estimate how many entries that would add up to.
Additional queries:
Do Bookmarks (the .HTML file of them) follow the same standardized format for pretty much Every browser out there ? I do seem to notice extensive similarities.
The Date Created info seems to reside in the individual bookmark entry 'Add Date' xxxxxxxxxxxxxx, such as ADD_DATE="1322971515" (?)
But I don't know how you decypher what each of these actually mean.