I used to use [a Windows 3.1 shrink-wrapped software package] that offered notepads and appointment calendars. Then I switched to Linux. That was 16 years ago. To take the place of the Windows application, I had to write my own list-maker from scratch. Today, there's a new python3-pyqt5 version (under GNU General Public License) of my script for Linux and Windows desktops to help maintain the equivalent of index-card files. Obviously this is not something you'd use just to be like everybody else. I use it because I don't really know how others handle their everyday lists and I can't think of an easier way. If you, too, suspect it ought to be easier than it is, it may be. Please look at Tonto2. Thanks.
I'm not familiar with jabref, so I probably shouldn't stick my oar in here. But I will anyway. I've written my own python script that I use for lists like Web bookmarks. It's a poor man's database manager, so you can add attributes to bookmark entries and sort and search on those attributes.