As of 27.6.2016, 'He was speaking with the judge' is still not accepted. I've reported it.
I would have reported it as "should be accepted", but I had an actual mistake in there as well...
Go raibh maith agat!
I’ve had my share of those situations too. In such a case, just check the last box (the blank one) and describe the problem there, without also checking the box that suggests your translation as an example of correct usage.
To me, there is a slight difference between caint and labhairt, just as there is between "talking to/with" and "speaking to/with".
I would use ag caint if they were having a friendly chat, whereas ag labhairt would be used for a formal communication. You could use either ag caint or ag labhairt in other circumstances, but at the extreme ends of the spectrum of formality, I'd see a difference.
I had never really considered that differentiation between "talk" and "speak", but now I recognize that that is a completely apt description of how I use those verbs. I talk with my friends, but I speak with my professors.