Apparently there is a cached conversation that didn't start properly in Cyseal getting triggered in Luculla.
Did you try killing the character in combat, maybe teleporting to the homestead, and resurrecting them?
If you load earlier saves and sneak through the fire area to get to Luculla Forest, is there a working save not too far back to revert to?
Please email email@example.com, with your latest save, and (if applicable) the most recent working save and the oldest where visiting Luculla triggers this problem (or a Dropbox or Google drive link, etc).
For Windows you can use the report.zip file generated by the D:OS EE Analysis Tool. Extract the zip file somewhere and run AnalysisTool.exe. When that loads, browse to the install folder (if it is not automatically detected), optionally run the tests first, and then generate a report (it will be saved in the same location as the Analysis Tool).
The report will contain system and game information, as well as your saved games. To reduce the file size, you can delete most of the saves from the zip (double click the zip file to open it in Windows Explorer, then browse down to the savegames and savegames_patch folders).
For OSX, saves can be zipped by right clicking the folder(s) and selecting Compress, in the folder: ~/Documents/Larian Studios/Divinity Original Sin Enhanced Edition/PlayerProfiles/<ProfileName>/Savegames_patch
Linux is similar, with the saves in the home directory.
PS4 saves can be sent, as well, but would need to be transferred to a USB flash drive first. In the Saved Data in System Storage section of the Settings menu, click Copy to USB Storage Device, select the relevant save(s) and Copy. From there you can optionally zip the files, then copy to email or upload to Dropbox or Google drive, etc, and provide a link.