Aoa. Problem solved today. I first checked sunroof drains by pouring water through drain holes:and water dropped properly through right and left side fenders.
Then I poured water on the plastic grill adjacent to wipers, some water abruptly appeared on the carpet of passenger side, at left corner.
I got opened the cowel plastic sheet under the wipers, but found no blockage or debris ets, channel was clear.
Then removed the carpet from passenger side inside the cabin, and strangely found that, a round rubber seal was absent on a hole, which was removed by ELECTRICIAN while installing wire of front camera. And he did not bother to re-place.
And rubber seal was also found under the carpet. So, got it installed. And poured water on windscreen and wiper cowel, Alhamdolillah no water.
I will further check it when get my car washed.
Leason learnt:No after market installation by CHAMPION TYPE USTAADS.