Here in Southwest Virginia I have heard cold back for what others call green broke. The only time I have heard proud cut is in a Western version of the Child Ballad, Black Jack Davie:
"Way out in old New Mexico
Along the Spanish line...
Go saddle for me the proud cut dunn
With the coal-black mane and tail...
Are these terms used in Australia, Canada or Great Britain? The use of "broke" as a past participle is, I think, archaic, so perhaps green broke goes back a long way.