It did skew radiocarbon dating in the form of atmospheric nuclear bomb tests. That's why carbon dating can not be used for very recent samples.
However, if these events happened in the more distant past, then they would show up in the calibration curves that are derived from lake varves, tree rings, and ice layers. It isn't there. In the graph below, the y axis is the 14C measured age, and the x axis is the actual age derived from counting tree rings, ice layers, and varves. The diagonal line represents constant 14C production through time. As you can see, there has been slight changes in 14C production through time, but it is easily controled for by the calibration curve.
If there were a cosmic ray event in the past, then we should see a big bump in that graph, but it isn't there.