If you run the group of JRadioButton tests, some of the tests fail:

jdk-dev> ./build/jdk-17/bin/java -jar ../jtreg/lib/jtreg.jar -v -a -ignore:quiet -w:build/jtwork -r:build/jtreport test/jdk/javax/swing/JRadioButton

The first two tests in the set pass:
javax/swing/JRadioButton/8033699/bug8033699.java
javax/swing/JRadioButton/8041561/bug8041561.java

The following tests fail:
javax/swing/JRadioButton/8075609/bug8075609.java
javax/swing/JRadioButton/ButtonGroupFocus/ButtonGroupFocusTest.java
javax/swing/JRadioButton/FocusTraversal/FocusTraversal.java

If you re-run the failing tests one-by-one, each passes.

The tests post Tab key to the Cygwin Terminal. The most likely reason for this behaviour is that the frame is not activated, the active window remains on the terminal and thus the test fails because it does not receive the required keyboard input.