As far as I know, they feel opressed being the minority in FBiH

Correct. They really feel opressed by Sarajevo, this is way they cooperate so much with RS. Herceg Bosna was a failure from the beginning. To create the Herceg Bosna Croats in BiH need the blessings of Zagreb, but that`s never gonna happen. Croatia is guarantor of the Bosnian integrity. So the dreams of HB are just dreams. Even the Croats in BiH are not united in this HB goal. A lot of them are pro-bosnian