It is hard to knock BIAB 'cos it does so many wonderful things, but I have always thought that it would be great, if when you chose a 3/4 style the Chord Window broke into 3 (6 with Chord Settings.

You can't use the 6/8 notation in the Lead Sheet for someone to learn a tune. 4/4 with 4 x 1/8 triplets is confusing (never mind 9/8) - especially as Celtic is read as normal but played in cut-time, e.g. twice the speed for the lead but as read for the backing.