The sentence works here, "at the cost of" can refer to the consequences of doing something. So in this case neglecting documentation and testing comes with the cost of communication, inefficiency, etc.
Incidentally as you allude to with their workforce aging out, Proton is prioritizing making money at the cost of their sanity
There is no long-term strategy though. Line's gotta go up in time for the fourth quarter, if it tanks next year that's next year's problem