The connection of Opensprinkler and the manual timer is not detailed enough on this drawing. Anyway, this setup should work. You do not need diodes D5..D8. D6 and D7 do nothing in this setup hence can be omitted. D5 and D8 can be replaced with a short circuit. D3 and D4 diodes makes the work, however they provide only half-wave operation. C1 shall be dimensioned according to this.
The D1 and D2 LEDs need a serial resistor.