ADA Compliance for PDF Forms: Tagging is changing the graphics - How do I change them back?

Hello,

I am currently working on making a PDF document ADA compliant. I tagged shadowed text within some graphics and it looks like it automatically brought the shadow part forward.  The text is now harder to read. 

• Is there a way to bring the shadow back so the graphic can look like it originally looked?
• Is there a way to tag text within graphics so it doesn't change how they look?

I have also come across issues in previous documents with images - tagging them totally changes how the image looks.

This form came to me as a PDF already so unable to make any updates or changes in the original document (if it is from word or any other program).

Thanks and Have a Great Day!