Wow, what a concept, readable colors and background - the field picker is really done right in Windows!
Yes, the black background, medium gray text on Mac field picker is the way it works, and is absurd.
I'm not aware of a way to change that but I would certainly be happy to hear if it can be done.
I'm a Mac user and have never seen this likely because I have yet to use the field picker. I use Insert field. Whatever colour it may be I don't find it a useful feature.
Any chance You are running an older MBS version (Plugin), the color in the system settings is set to grey? (change to yellow)
Here is an AppleScript that toggles Apple system preferences on contrast, that makes the field picker dialog workable; not tested in FMP16 as yet.
tell application "System Preferences"
reveal anchor "Seeing_Display" of pane id "com.apple.preference.universalaccess"
tell application "System Events"
tell process "System Preferences"
click checkbox "Increase Contrast" of window 1
click checkbox "Reduce transparency" of window 1
tell application "System Preferences" to quit
You will need to allow script editor to on in accessibility settings under "Security and Privacy" to work.
If you compile it, you will need to allow the compiled applet access, access under accessibility settings in "Security and Privacy" to work.