First off, you guys are doing a great great job with JabRef, and while I don’t use it as I already have a long-term workflow (Bookends on macOS / iOS), I do suggest Jabref to students and others.
While helping someone on the Scrivener forums, the best workflow for this external editor was to install GitHub - teertinker/JabRef_LibreOffice_Converter: A LibreOffice extension that converts JabRef references to plain text code and vice versa so that you can use your references with MS Office. and then use the LibreOffice integration pane. It seems to me that rolling in the plain-text <-> tem-field-citation function into the JabRef Libreoffice panel would make this workflow slightly simpler; there are reasons one may want to convert temporary citations to plain text and back and having this rolled-in would be helpful…