Catalytic Converter Install, did I damage the exhaust manifold? 200k miles

So, I ran out of the 1000 words and couldn't detail more all around. It was not really clear when I said cata code appeared but did not say the previous errors disappeared. I apologize. As well, did not mention that previous to this the spark plugs, coils, and wires were all replaced before the fuel injectors were replaced. Many other things, the MAF, pressure regulator, fuel pump. The codes remained. Upon replacing the fuel injectors _this did fix the misfire and too rich codes_ but introduced a catalytic converter error code. Upon replacing the catalytic converter the codes have appeared again. So let me re-ask the question. Did putting pressure on the EGR Exhaust Manifold possibly have damaged it, causing the codes to appear, not from plugs/coils, but from a leaky exhaust manifold? To the question at a more fundamental level: During the catalytic converter install, is the downpipe (EGR?) from the exhaust manifold supposed to move at all during mating? Cylinder 5 is on that side of the exhaust manifold to which budged/swayed during installation of the bolts which connect it to the catalytic converter on the side. It's the middle cylinder on that side, most likely to crack in that area, mid manifold. Oh, also probably important, the RPM gauge/sensor is no longer working.