During my brownout I tested few CFLs, only one lit the gases of the ends and the other ones just did't turned on.

Couriously when I approach my hand to the bulb the lit gas area increased due to my hand capacitance by some reason. When my hand was close enough the CFL lit with a mains flicker and then came back to the initial state. I did this until the CFL warmed up and when the light was constant the CFL was dimmer and with a 50Hz mains flicker?

Why did this happened?  

May you describe more in detail how exactly the setup and/or situation looked like?
What supply was connected where,...
Because I could not follow your too much shortened description...

I think the missing part is knowing that brownout is technically defined as a reduction in supply voltage. Presumably OP was attempting to run the lamps well under rated voltage.

Your body acts as an antenna to pick up and re-radiate mains frequency. Touch an oscilloscope probe tip to visualize this. I would guess capacitive coupling of this voltage superimposed on the (lower than optimal) open-circuit voltage of your ballast allows momentary striking of the discharge in sync with mains.

Frist: My brownout was a voltage drop, not a current aviable drop.

When I powered the CFL directly to the mains, only the lamp gases near to the cathodes glowed, so the cathode coating substance was working, when I approach my hand the glow area increased and then the CFL lit dim and came back to the initial state a few seconds after removing my hand. I repeat that cicle until the CFL was be able to keep its arc by itself, and when the CFL was working by itself I noticed the mains voltage flicker.

The CFL was this. The lamp used is 20W, 220V and triphosphore.

I think my hand capacitance helped to drive the cathode coating electron emmition across the lamp. The mains voltage was way too low for affect the CFL throug my body.

The static electricity on your hands, ionized the gas inside the tube, so it transformed from partial glow discharge to a cold cathode discharge.

The inverter in the CFL is running, even in the undervoltage condition. It generates high frequency (10's kHz) AC, which is applied to the lamp electrodes

If we look at the voltages on the lamp electrodes relative to outside ground, the voltages are :

Cathode 1 : HF voltage with up to 320V swing (at normal supply voltage), superimposed on rectified line voltage of 50/60 Hz

Cathode 2 : Rectified line voltage of 50/60 Hz. (Through a capacitor, but it does not matter as long as there is no discharge in the lamp)

The capacitance between the Cathode 1 and your hand conducts some AC current. The significant effect happens on Cathode 1. where the HF is. The current is coupled from the electrode to your hand, and is significant enough to extend the discharge area in the lamp

If the discharge area extends significantly, the voltage applied between the lamp electrodes may be sufficient to take over the discharge. But if the discharge is unstable, it will go back out

The circuit is not very symmetrical in polarity : The cathode in the lamp is a better cathode than your hand from outside. The half bridge in the inverter in most CFLs is incomplete - only one capacitor is present to one pole of the rectified line voltage. The HF is superimposed on the rectified line voltage. This all means, that under some conditions the main discharge will be able to take over when the partial discharge is in one polarity, but not when it is in the other polarity. If this happens consistently, the lamp will flicker at the lamp frequency