People may already have worked through this, but none of the workarounds posted here seemed to work for me. Here's what I did with a few edits to the Moneydance launch script:

Based on advice in https://askubuntu.com/questions/687919/how-to-make-java-gui-programs-look-more-modern, I added to the launch line (382) the following argument:
-Dswing.defaultlaf=com.sun.java.swing.plaf.gtk.GTKLookAndFeel

Looked much better--not only was it readable but I could drop the Font Size in preferences to about +3. I kind of assume that part of this was having tweaked the GTK settings to look good on my screen.

I've not extensively tested so YMMV. I also haven't found an exhaustive list of LookandFeel options. I can also report that OpenJDK 11.01 works; edited Line 4 to point to it:
  INSTALL4J_JAVA_HOME_OVERRIDE=/usr/lib64/java-11.0.1
(There may be Java glitches with this version; I haven't exhaustively tried everything.)

I'm just a user, not official support. I thought people might be able to use this. Editing the launch script may not be for noobs (make a backup of the original!) but many of us on Linux can probably handle it.