[Spot The Difference (Oxford)]

Does anyone know how to remove emulsion paint from a leather sofa?

[LTT Leathercare]

Paint spillage

The secret is to act quickly whilst the paint is still wet. Remove the excess using a knife or wallpaper scraper, taking care not to scratch the surface, and work form the outside in to avoid spreading it further. Once the bulk is removed, mop up the rest with a cloth or paper towel, again working from the outside. Finally, clean the area with Strong Cleaner.

This is a tricky problem once the paint is dry. Try cleaning the area first with Maxi Cleaner. If it won’t come off with this, then there’s nothing you can safely use without damaging the leather so the job becomes a restoration job rather than a cleaning one and you will need to be confident about repairing any damage that stronger products will do.
If you are confident to repair the damage use Alcohol Cleaner next and see what this does.  If this does not completely remove the paint use Remover 3 which may remove the paint but if it does it will also remove finish/pigment which will have to be replaced.

Hope this helps