As a Roblox developer, it is currently too hard to make advanced looking painted terrain because of the very small amount of customization for colouring your terrain.
If Roblox is able to address this issue, it would improve my development experience because I can make better looking terrain with multiple coloured terrain of the same material.
Basically this feature would show in the edit tab under presets in the terrain editor. It would show your presets and a button that says “New” where you can create a preset using already existing terrain materials or custom textures and you can customize the colour. Instead of only being able to have one grass for example you would be able to have multiple with a different colour / texture.
I think this would help tons of terrain designers / builders including myself and would give many games much more variation when it comes to terrain.