Well I accidentally went into the EU lane 2 weeks ago (because for some reason the EU lanes were located right next to the kiosks).
But the officer didn't tell me to go to another lane and only after starting the photo/fingerprints he said "did you realise you are in the EU lane, I'm not sure if the EES machine works as I haven't used it yet", but it did work and it was fine.
Which airport was it? I may try that in a few weeks with my spouse in NCE...