How to calculate maximum amount of bulbs I can connect in parallel to match design specification of 1.5 A?
The power factor (PF) is a keypoint here.

If it was nearly 1.0 then the calculation method you've shown in the original question would be acceptable.

But since it's around 0.5, things change a bit:

Apparent Power = True Power / PF = Power [in Watts] / 0.5 = ~ 2 P

So the apparent power of a bulb will be 8VA. So the current drawn from wall socket will be nearly 8VA / 220V = 36mA

So, if 1.5A is a limit then 1500mA / 36 = 41 bulbs can be connected in parallel.

BUT! 

Since the power factor is low, the inrush current (the current drawn for a short time right at the turn-on event) will be extremely high due to the parallelled bulbs. You can fairly estimate 200 Amperes for a few milliseconds. You should also take this into account.

PS: IIWY I would connect max. 10 bulbs in parallel.