I feel I understand perfectly now and already feel much cleverer.
I won't make any changes or ask my host to do so.
I've been to vote in the Tracker for MDL-16474, but see very few of us have. I'm amazed! It's so obviously the right thing for adult education situations and we have the example righ here on Moodle.org.
I have a workaround. I've put a smiley as the second item which seems to me to be as positive and non-judgemental as "useful". I haven't tried it out with live participants yet. I'll let you know if it works.
Thanks a lot.
Cheers,
Glenys