Exterior patio door installed without header, jack or king stud framing

Hello, a friend of a family member recently did a favor and installed used patio doors in my family member's house, replacing an existing fireplace. He knocked down the chimney, removed the fireplace insert (probably c. 1960s era, as is the house). He then cut out an opening into the brick exterior to fit the doors. He also cut the cripple studs and the king studs that framed the fireplace to create an opening in the framing, then inserted the doors into the opening. To neaten up the top gap he left, he nailed a plank of wood to the exterior face of the cut studs. Apart from that there was no other timber framing added. The door is about 70" wide and the wall is is about 20 foot wide overall. The house is a single story, brick clad house with tin roof. Is there a reason to worry that the structure is unsafe? I imagine the door will fail at some point, but that's probably to be expected? We're most worried about the safety aspect considering this does not appear the proper way to do the installation. Please excuse if I'm not properly describing the job. I have no building experience.