The circuit is completely wrong, fortunately you are operating it only in a simulation, otherwise you'll see a lot of smoke.
With transistor opto couplers, you need a separate trigger power supply for each SCR cathode node, four in this case. Trigger transformers are a usual means, also opto triacs (e.g. MOC3020) can work, they need a series rectifier diode to block negative voltages. Or use four triacs instead of SCR pairs.
To mention a possible problem, triggering a cycloconverter wrongly will short the power supply and cause catastrophic failure.
I would never connect a LED without series resistor, even in a pure simulation circuit.