applying anything with a volume to a flat surface will never work, the shirnk wrap modifier is ment to be used for retopology, snappnig flat objects to flat surfaces, or snapping a volumetric object to another volumetric object that is entirely inside of it.
if you want it to look like a sticker, then there are a few ways you can do it. personally, i would start over, because you are clearly using a very destructive workflow, with text and boolean. either that, or make sure you do it in the right order.
first you create the sticker, this can be made flat, then shrinkwrapped on to the surface, or you can create a volumetric object and simply just model it as close as you can, using a subsurface modifier to get rid of any jagged lines.
then after you’ve done this, you can proceed with the boolean operations.
also, a sidenote, watch your normals. i happen to notice that the knot on the bottom of your… whatever that thing is… has its normals inverted. look at the bottom right of your image, the thing has a very dark shading, this is bad, very bad. select it, and do W+F to FLIP the normals, or you can do CTRL+N to Recalculate the normal.