Yes, "acetal" is some type of plastic, and the original failures were related to the acetal inserts and the associated crimp rings. It was later found that the tubing itself is not suitable for hot water service, so the problems continue for those houses which still have it installed. And that is why there are still a series of fittings to repair PB and to join it to copper. I have not seen an adapter to cpvc, but it may exist. I believe it would be glue the cpvc, not compression.
You mentioned "new PB". I am not aware that there is any new PB. It has been decertified almost everywhere for residential use. It may still be allowed for underground service mains, but I think that application has mostly been replaced by polyethylene and PVC. The QEST line of adapter fittings is still available for repair and retrofit applications.
To get specifically to your question: you need to join copper to CPVC. FIrst, the cpvc connection will be a glue joint, not compression. No problem. (There may be compression to CPVC fittings, but I would only use glue in your situation) All the adapters I have seen are either sweat to copper, or IPS on the plastic adapter, to srew into or onto a threaded copper adapter. I believe if you insisted on a compression connection to the copper, you would use a compression X IPS adapter on the copper and a slip X IPS on the cpvc.