I can understand your concern, however please the informed the workflow to change the color of commenting tools on iOS devices will be after Saving the changes and then selecting the content that will provide you the pop up with the option to change the color of the content.
On the other hand in Android devices the change color option is available as soon you select any of the commenting tool.
We can surely take it a feedback.
If you would like you can also post your suggestion here :- Feature Request/Bug Report Form
The developers will actively take the ideas that will have the greatest impact and implement them. Posting your idea there will give this suggestion more steam to get it implemented.
Cool! Thanks for the explanation!