1. If mixing valve is turned fully counter clockwise then the water should be fully soft. When you turn mixing valve clockwise then it starts to add hard water to inlet soft water. You can see mixing valve in the manual. Level of hardness you need to adjust with hardness test kit.
2. If you cannot increase hardness more than you need then please try another thing. Open two red valves on bypass manifold about 45 degrees. It starts to mix hard water from inlet with the soft outlet water. You can open and close the valves as much as soft water you need. If they are completely closed, then the water is just hard. If they are fully open the water is only soft. So something between that should mix the water.