Do you have any product that would clean up the splotches I have made on raw (taupe-colored) canvas with acrylic paints and extra heavy gel?
Acrylic paints are pretty hard to get off of a painting, especially raw canvas and paints with a high tinting strength. Strong solvents like acetone, if used carefully (acetone is highly flammable and very dangerous to use without sufficient regards for safety) with a cloth that can soak up and lift the paint film can work, however, most pigments are going to stain the canvas and you'll still have a discoloration. You may have better luck removing the gel, but generally speaking, there will probably remain a stain like appearance unless you are meticulous and can remove every last bit of it.

If the raw canvas is shown throughout the painting and it is a border section isolated from the intended painted area you may be able to lift off the films above the surface, and then use GOLDEN High Load Acrylic Canvas Color over any raw canvas areas. If used thinly and evenly, most viewers cannot tell the canvas color from raw canvas, but my experience has been that if the two are right next to each other, the difference would be apparent, as canvas colors can vary from roll to roll.

Some people use GOLDEN Matte Medium and Fluid Matte Medium as "transparent gesso", and had you had done this layer, the pigment would not have stained it. I mention this as an after thought. Raw canvas, unless cared for very well in a controlled environment, will begin to suffer the ravages of time as will any uncoated cloth.