This is the section most TRIZ training leaves out, and it is the reason TRIZ output sometimes reaches a steering committee dressed as a decision.
The matrix does not check that your contradiction is real. It looks up whatever pair you set. If the conflict does not exist in your process, you still get principles back and they look just as convincing. It does not check that your root cause is proven either. TRIZ is a solution generator. Point it at an unvalidated cause and it will generate solutions for a guess.
It does not tell you whether the idea is worth doing. There is no cost in it, no effort, no risk, no feasibility. Nothing here ranks anything. And it does not give you a design. Principle 24, Intermediary, tells you to put something in between. It does not tell you what, who builds it, or what it costs.
It also has gaps. Around one cell in six is blank in Altshuller's original, and a service contradiction will sometimes land in one. The matrix cannot resolve a physical contradiction at all, where the same parameter has to take two opposite values, and for those you work from the separation principles instead: separation in time, in space, on condition, and between the parts and the whole.
Finally, the contradiction matrix is one part of TRIZ. Su-Field analysis, the Ideal Final Result, ARIZ, the 76 standard solutions and the trends of technical evolution are a much larger body of method. Anyone presenting a matrix lookup as a full TRIZ study is overstating it.