What process is going to help senior contractors understand the codebase they've been in for 2+ years? We can create spike tickets all day, but at a point, that's just a distraction.
My point is Every single item on your list is fixable, don’t attempt to fix every one, start small and create a roadmap, and timeline. Hold people accountable especially contractors. You’d be amazed how quickly things get better when you hold people accountable.
So sorry, that was auto correct on the phone. I meant SDLC, the software development life cycle, and most probably the Project management methodology. The symptoms you describe are synonymous with a disjointed organization that lacks good processes and communication. You are correct to bring it up to management and definitely YOU are not the problem.