Weak Breaks - Need Help Diagnosing

[75sv1]

My take. The previous job looks hacked. The routing of the rear lines, is suspect. Makes about anything less, questionable. Yeah, I'd put new calipers on the front. I went through this with my Chevy Avalanche last year. Looked like recent parts. I found chunks in the Master Cylinder. I botched a new one. I didn't bench bleed it right. I also had a '78 Civic. Had the brakes replaced a few times. The rotor on those were pressed between the bearing. They didn't bleed the front calipers. When I did, there was a rust blob that came out. Yeah, new calipers.