I am also a comparatively recent user of hearing aids, but so far only have 2 settings on mine "normal/automatic" and a quieter setting which does eliminate some of the background noise that you might get at a ceilidh. Several of my musician friends have a "music" setting, which they have encouraged me to ask for at my next check, as it makes the tuning sound better, rather than the somewhat tinny sound you can get on automatic. I don't have a loop setting as the automatic is supposed to cover that.
As an engineer, I'm sure you'll be aware that band members are often sitting behind the speakers, where speech through a mike from a caller on the floor or other announcer can sound really distorted, to the point if becoming unintelligible at times. And, especially if they are using a cabled mike, feedback can be a problem if they move to the wrong place near other equipment.
And at the risk of sounding frivolous, as another hearing aid user friend said, " If you don't like the music, or it's too loud, just switch the aids off, but leave them in as earplugs"!