I'm very surprised to learn there isn't anything in the 32 counties?? There must be lots and lots of learners in Ireland, (it's not a small country, is it??) without having to fork out air fare across the Channel?
There was one in Northern Ireland but the numbers were small... and that included 4 who travelled across the sea.
Though it might be a great thought to have events everywhere there are things to take into consideration.
One is that someone has to take the initiative to organise things but this is not the whole story.
Currently I think that most events are viable because of travellers from outside the immediate area. I think that Katyjay's Adult Learner concert is possibly the one that has now attracted enough people from the 'local' area to not be relying so much on those coming from a distance. Local area is quite wide too.
You have to take into account that not everyone who is shouting for an event nearby will attend if there is one for various reasons. Also with a relatively limited number of people who will attend events regardless of location if there was one everywhere on a regular basis there would n't be enough people to go round and non would cover costs or have enough attendees to make a reasonable concert.
One possible knock on from these events is that it may become possible to organise similar local events but attracting local adult learners who are not forum members. Form my experience this can be very difficult to get going.
One consideration with event venues is accessibility by public transport making it possible for more people to get to one or another.