Does Illustrator’s upgrade installer preserve third‑party plugin manifests during a failed upgrade?

When an Adobe Illustrator upgrade fails, users can revert to a previous stable state by restoring the Adobe Illustrator Prefs file or using the Illustrator Recovery folder. However, the upgrade installer does not automatically back up third‑party plugin manifests, which may leave plugin menus missing after a rollback unless the plugin folders are manually copied from the earlier version’s installation directory.

What manual procedure reliably restores third‑party plugin manifests after a failed upgrade, and does this procedure preserve all plugin settings without introducing conflicts? Are there any known limitations or side effects when copying plugin folders from a previous Illustrator version to restore menus?