If you are playing on PC, please email supportdos@larian.com with your save at there (or a Dropbox or Google drive link, etc), and I can teleporting your party past that test, which should let the end of the trial work properly.
Each save is a folder in the '..\Documents\Larian Studios\Divinity Original Sin Enhanced Edition\PlayerProfiles\<ProfileName>\Savegames_patch' folder.
In Windows Explorer you can zip a file or folder by right clicking on it/them and selecting 'Send To | Compressed (zipped) Folder' (and similarly in macOS; in Linux the saves are in the home directory).
On console, did you try reloading a save before first entering Luculla Forest, if available? Unfortunately, there is no way to get a save off an Xbox, and console saves are locked to the account used to save the game, so there is no way to return a fixed save that you would be able to load.