Both .cdr4 and .bpt files are used in CorelDRAW and this might be actually the only software that can be used for cdr4 to bpt conversion of any kind. This is usually the case of export of very old / rare files from some ancient version of Corel software. Latest versions might no longer support old files in which case you will have to find old version of Corel or contact their support for help.
Updated: August 4, 2023