If you have used Photoshop to make tileable texture, you are probable familiar with the Offset option. If you switched from Photoshop to Pixelmator Pro, like I did when I switched to MacOS, you may be wondering where the option exists. It does exist and is an Effect. Instead of offset, it’s called Affine Tile.
(From the main menu Format, or from the Add Effects)
Effects -> Add -> Tile -> Affine Tile
This will take your image and perfectly offset so that the edges are aligned to the center of the image. It’s effectively the same as Photoshops Offset with the wrap around option set. Once wrapped, heal/overlay etc to remove artifacts and your texture will now tile more seamlessly.
Of course there are a few options you can modify here, but the defaults get us a perfect offset to clean up our edges.
Note: Be sure to flatten/group and work with layers appropriately when applying. Whatever works best for your workflow and required output.