Here are a list of issue I have seen related to key navigation.
I'm not a a11y expert, so please correct my assumption if needed.
All these issues are impacting Scene Builder.

Note that the first issue is related to SplitPane: by default, its focusTraversable property is true. In this case, the Tab navigation does not allow to enter in its content. To workaround this, the focusTraversable has been set to false for all the SplitPane of the test case attached.


Open the attached fxml file in Scene Builder
To see content in ListView and TableView, select from the menu bar: View>Show Sample Data
Preview (Ctrl-p)

The focus is in the top TextField
Type several Tab to go to the "untitled 1" TitledPane
Type Return to open the TitledPane
Type Tab
=> the first item of the ListView should be selected
Type several Down Arrow to move in the item list
Type 2 Tab to go to the TableView
=> the first item of the TableView should be selected
Type several Down Arrow to move in the item list
Type Tab to go to the "Synopsis" TextField
Type Tab to go to the TextArea
Type Tab to go to the MenuButton
=> the TextArea should not capture the Tab event. No way to go out of the TextArea using keys
Select the MenuButton below
Type Down Arrow to go to the first CustomMenuItem TextField
=> the TextField should get the focus
Select this TextField
Type Tab: the MenuButton is selected
Type Tab again
=> the popup is closed, when the 2nd CustomMenuItem TextField should get the focus