I wonder if something is going on at Apple's end, where the Siri processing gets done.
Thanks for your many years of attention and everything you've done to make the site such a valuable resource.
I sometimes find the Java setup on my various Apple devices to be a mystery.
To fix things for the moment I simply removed the jdk folders.
And then checked that the reported version of Java was 1.6 on each Mac.
The first thing is that you have to do some configuring of both Java and Safari to get the applet to run at all.