JabRefIn a large open source project, unfortunately, it can happen tha solving an issue may take a while..
We are pleased to announce that a longstanding 6-year-old annoying issue with using keyboard shortcuts in the BibTeX code text area got fixed
https://github.com/JabRef/jabref/issues/5937
Side effect: people in our team also learned about these nice macOS keyboard shortcuts for navigation and text selection.