Calculation focumla check- ISO Math Experts

I like to consider myself a math expert, but I am not sure I can give solid answer to your question. Part of it could be that this looks like business math which I am not familiar with, and part of it could just be the ambiguity of what "percent change of a percent change" means. Even though I don't know "The Right Answer" (TM), I will offer a couple of thoughts and bump this back to the top.

Wikipedia has this article: https://en.wikipedia.org/wiki/Percentage_change that has a short section about "percentages of percentages" that calculates the percent change in a percentage the same way that you do. If you are comfortable with this as a final authority, then maybe that is good enough.
This discussion seemed less conclusive and discussed the ambiguous meanings of "percentage change of a percent change". https://www.quora.com/How-do-you-cal...-2-percentages

This might be a good question for a supervisor or co-worker rather than the internet. Your company may have a preferred way to calculate and express these percent changes. No matter what any of us think, if your employer has a preference in this case, I would encourage to follow your employer's preference.

As fodder for additional discussion and thought -- what do these "percent changes" really mean (above and beyond "the ratio of 6:8 is 0.75 or the ratio of 5:2 is 2.5")? Looking at one extreme example -- G10 shows a 150% increase between 2% and 5%. Mathematically, I can see what that means, but I expect there is really more to what this means and what you are trying to communicate here.