Line E does go to Bolhão, it even goes as far as Estádio do Dragão. It's just that some metros on line E end at Trindade, and some end at Estádio do Dragão (please see the timetables at https://www.metrodoporto.pt/metrodoporto/uploads/document/file/720/horarios_web_20_07_2024.pdf, page 21).

This route relation needs to be split into two route relations, grouped under one route_master.