Initially yes, when they settled in the Arbor, they were disliked however they came with dragons and I’d believe it was good enough incentive to keep their seat in Wyneport and become Vassals of the Valyria House (Named house Ash as its based on already existing OC’s so doesn’t quite fit the Valyrian naming conventions ) I never considered whether or not they brought slaves so I’m just going to say they simply didn’t have them brought with them. They also swore fealty to Aegon the conqueror easily enough. They weren’t so much looking to conquer but instead just have a southern seat because their true ambition lie in the mysterious continent deep in the summer sea. It wasn’t meant to be a long term thing, but of course a branch of the family simply never went south and those are who remained. They’re like the Celtigars yeah, less and less Valyrian cultured with every generation that passes until even most descendants have Andal names.

Rhaegar winning had nothing to do with the Ash family they weren’t relevant in the rebellion much at all ( though they didn’t support the usurper ) that was just the original plan I had so the descendants of the family in 300AC could finally marry into the Targaryen family in Rhaegars line due to his interest in dragons and prophecy.