For any other converter I'd tell you to grab provinceMapper and load the province mappings from inside the converter and relink whatever you wish, or do it manually even.
CK3 is special because we don't map baronies at all, we map counties (due to a difference in resolution). We take all baronies from a county, name the county with the lowest ID of all baronies within, and link that to EU4's province.
And to do that using our provinceMapper tool, requires running a special program (mapDegrader) that repaints the entire map and produces alternative definitions.csv etc etc.
In any case, you can still do this manually, but I fear the differences between maps may be significant and impossible to handle via hand.