I was tried a few different things trying to remove the acrylic grout residue, sulfamic acid didn't work, but Soft Scrub with bleach worked really well!
Just apply it to the tile and scrub with a white scrub pad or stiff bristle brush then wipe with clean water. It takes a little effort,but it removes the residue and really brightens the grout joints. Give it a try and let me know what you think. Thanks.