@mkaut I could not manage to work on this.
Please open an issue at GitHub · Where software is built so that we can track it in our normal issue handling. I think, your steps are enough to post on the issue. It would be good to also have the error also as screenshot. That way, it is consumable by freshman and we can label it as “good second issue”.
Regarding the difference of “replace unicode ligatures” and the unicode-to-latex should be a different question. Someone needs to go into JabRef’s code and update the documentation accordingly then.