OK, so I'll stick with my own convert-ly files as I'm on the stabgle version.
Problem now seems to be that the positioning tweak in
persian.ly such as "persianStringsXExtents" is no longer working correctly with my file. Strangely the YExtents and Offset work fine, eg if I make Y-Extent large the beams move out of the way.
persianStringsXExtents = #`(
(-3/10 . (0 . 1) )
(1/5 . (0 . 1.8)) %<--- this should control how "wide" the koron is but it has no effect
(0 . (0 . 1))
(1/2 . (0 . 1))
(2/5 . (0 . 1))
(-1/2 . (0 . 1))
(-3/5 . (0 . 1))
(-1/10 . (0 . 1))
(-1 . (0 . 1.8))
( 1 . (0 . 1.3))
)
\override Accidental.X-extent = #(lambda (grob)
(cdr (assoc (ly:grob-property grob 'alteration)
persianStringsXExtents )))