If they occur in response to environmental stress and the increased mutation rate helps the organism to adapt to that stress then possibly it is goal directed. The goal is to adapt to the stress.
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So long as you remember that does not mean 50% harmful and 50% beneficial. The vast majority of mutations are detrimental, probably including those that code for the same amino acid.
Do the regions that experience increased mutational rates during stress change the ratio of detrimental to beneficial mutations? If not, then mutation is still random with respect to fitness.
It's a reasonable hypothesis based on the observations, and should not be excluded at this stage.
That certain regions are prone to higher rates of mutation and that environmental stress can increase mutation rates in target regions is a known and accepted phenomenon. That is not the same as mutations being "goal directed."
There is some evidence that even where the mutation codes for the same amino acid it can affect other things such as the rate of production.
Keep in mind that in order for a mutation to affect fitness, it must affect the organisms ability to reproduce. So while a mutation that codes for the same amino acid may have energetic effects on a bacterium that may slow it's growth rate enough to give it a slight disadvantage compared to others without the mutation, it is unlikely to have a significant effect on larger organism such as humans.
HBD
Whoever calls me ignorant shares my own opinion. Sorrowfully and tacitly I recognize my ignorance, when I consider how much I lack of what my mind in its craving for knowledge is sighing for... I console myself with the consideration that this belongs to our common nature. - Francesco Petrarca
"Nothing is easier than to persuade people who want to be persuaded and already believe." - another Petrarca gem.
Ignorance is a most formidable opponent rivaled only by arrogance; but when the two join forces, one is all but invincible.
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