Electrical – DC to DC power supply Virtual Ground circuit dillema

Yes. I've used the term "virtual ground" for a node used as reference for signals and that was generated by making roughly a mid point between two supplies. I think that's pretty common usage.

I also agree that "virtual ground" can be used to describe the negative input of a opamp in inverting amplifier configuration, but only when the positive input is tied to ground.

This is a loose enough term that it should be defined before use, unless it is clear from context. Talking to someone about virtual ground without context or a definition is wrong.

First of all the phototransistor seems to be drawn upside down, the emitter should be at the negative side.

In your circuit, the inverting input is held at the virtual ground potential by the feedback loop. In order for the output of the opamp to be made to go positive, current must be drawn from the circuit node to which the inverting input is connected. This will cause the inverting input to tend to go negative and the output voltage will rise, causing current to flow (to the left) through the feedback components thereby restoring the voltage at the inverting input terminal. In order for this to happen the phototransistor must be connected to a more negative potential than the virtual earth. The "true ground" would be a suitable point. If it were returned to the virtual ground, then there would be no potential difference across the transistor and the circuit would not work.