There are basically two kinds of dialect writing, one where the text is entirely written in dialect and one where it is mainly in the spoken passages. M. E Francis' writing is of the second kind. Having grown up in Manchester, some Lancashire pronunciations do not trip easily off my tongue, and anyone who cares to listen will here me struggling to say 'old' as 'owd', 'home' as 'whoam', and to manage 'running t' th' gate' with a soft 'th' and without enunciating the vowels in 'to' and 'the'. It is not so much the pronunciation that is difficult as making it all flow.
Perhaps I should get myself a dialect coach, but until I do I must thank Philip Dunkerley for his excellent pages on Lancashire dialect and especially for his mp3 recordings of Lancashire poetry, which have been the greatest of help.
I have also come up with two rules - I don't know if others would agree.
(1) Read what is written on the page, even if it appears to be inconsistent or wrong. This is reading aloud, after all, and it is not for me to correct authors if I think they have their dialect wrong.
(2) Concentrate on the flow of the words and don't worry too much if listeners will understand the dialect or not. After all, these books were written to be read and if the authors thought they would be understood, who am I to differ?