As mentioned in the following two links, JabRef ships their own version of JavaFX. It should not be dependant on any JavaFX version installed on your system. Maybe there you will also find some clues on how to make it work for you.
- "Failed to launch JVM" error prevents JabRef to startup - #5 by rrodrigueznt
- JabRef 5.3 jar file - #6 by ThiloteE
Also, here is the official FAQ for installing jabref: _https://docs.jabref.org/installation
Sorry, i can’t help you more. Currently I don’t use a rhel7 system.