Also, when you listen to early recordings of Micheal Coleman, the renowned Sligo fiddler, the piano player that accompanied him was either drunk at the time or completely unknowledgeable about the melodic implications of the music.
very true,
some of the BC ACCORDION PLAYERS are bizarre as well,playing in a dorian and using A major basses.
so sometimes the choices are wrong,sometimes there can be more than one correct chord progression.
what I do find interesting are some of the alternatives to the dominant seventh,a minor chord based on the fifth of the dominant seventh with added notes,or a series of minor thirds for example for g7,d f g# b,or my favourite the dominant 11 substitution.,how these work obviously depends upon the melody notes.Dick Miles