Painting textures in 2018.3 very pixelated

So with the new terrain, it became really hard to hand-paint the splatmap with any of the brushes.
Where before I could use the "Target Strength" slider to make very subtle layers on top of the existing image, it now works as zero-one solution. The new splat either doesn't show up at all, or immediately shows up as a 100% opacity dot.

On top of that, in my case - I have a 7000x terrain, and a max possible (2048x) control map set for it, so the edges of the brushes become very ugly and pixelated.

Is there any workaround for this? In 2017.x terrain there still was a "Target Strength" setting which would let me hide these artifacts, now this is a broken workflow.

Maybe a 3rd party tool, that makes hand-painting easier? I'm not interested in any rules-based tools, I have to fine-tune my terrains myself.