You can use the new mod for refind and refindplus it is designed with old firmware support in mind, give it a try: https://github.com/aterro/rEFInd-for-All/tree/master/Release or https://github.com/Abz79/RefindPlus
You can use the new mod for refind and refindplus it is designed with old firmware support in mind, give it a try: https://github.com/aterro/rEFInd-for-All/tree/master/Release or https://github.com/Abz79/RefindPlus