So I set this text to change the bottom layer to concentric only for the text and I got this. I had this large flat area in my print and decided to spice it up a bit for fun without doing multicolor which would be 1, too annoying to do manually and 2, too visible for this part that needs to be all black. So here I have a nice DON’T PANIC on the back of it.
Please indulge me.
With a result like yours I’d honestly just start from the top of Ellis guide and follow through to the end, that should help you fix this and get a significantly better print quality. There’s likely a lot of things that are less than ideal, fixing only one or two won’t be enough.