Water was always coming in at the sides, so he is not wrong there.
One more time, look at what you quoted.
The ship mechanic Henrik Sillaste was on board Estonia and far below deck when the ferry first got into trouble. He then went up to the control room where two other engineers told that the ship took in water via the bow.
Next to all panels and meters there was also a black and white monitor that showed camcorders from car tires. There he could see with his own eyes how water rushed in next to the ramp at the front.
Two of his colleagues saw after a while how the water covered the car tires and later how it splashed up over the camera that was in the ceiling.
He went to the control room because of an apparent emergency (at least, the ferry had "got into trouble"). Other engineers told him that the ship was taking in water via the bow. The next two paragraphs are about an influx of water.
Okay, so if this water were normal, why did he go to the control room and in what sense was the ferry "in trouble"? If there was a fire and the sprinklers were going off, why did these two engineers tell him about the water coming in from the bow (which you claim was normal)?
Surely, after the pleasantries about the water coming in (which was totally normal), they should have at some point mentioned the fire and/or sprinklers. The alleged fire wasn't normal, was it? Wouldn't mention of that spice up a conversation?
But no, it went something like this. The mechanic went to the control room after the ferry got into trouble.
Two engineers said to him, "Say, Henrik, you know that water that's always coming in around the bow? Well, it still is and in amounts that are not at all surprising or indeed noteworthy."
Henrik then watches for a while, observing the water cover the car tires and water from somewhere, splashing on the camera. He thought nothing of this, of course, though he did mention it to the interviewer much later. He of course recognized that it was a sprinkler and hence there was a fire at that time as well, but he knew the interviewer wouldn't be interested in such trivialities. Best to focus on the normal leaks at the bow which on that fateful day were ominously normal. No increased flow at all. The same as every other trip. Boy, that didn't bode well... He decided to draw a picture of the water's ingress to show just how startlingly usual it really was.
Does that sound about right?