So, all Carplay apps are inherently limited in how much data they can display in a list. It’s somewhere between 200-250 items for ARC as of now. This is an apple limitation, not an ARC limitation.
Right now, browsers inherit your sorts from the ARC app, so if you’ve chosen to sort your artists alphabetically, Carplay for ARC will do the same. For a quick alternative, try changing your sorts in ARC, those should manifest in Carplay.