I replaced the controls on both my Tecmas because I wanted to have more control, as others have said. Initially just 2 buttons as above, water and pump. But while that worked for me, guests often pumped without enough water leaving things high and dry (as it were), which is the reason for the original control of course.
I now have one button just for water fill, while the second button does water at the same time as pulsing the macerator approx 1/2 second on, 1/2 second off. I find this covers all bases - the rate of water flow matches the speed of ‘taking away’, keeping everything moving nicely and without using more water than necessary. I used a mix of 24v timer relay, normal 24v relay for the solenoid valve, and high current solid-state dc relay for the macerator.