From Polish sources (Klich) it follows the crew knew they are below the decision point, as the voice was saying "90...80..."
It is unclear why they continued on autopilot even after that, where they thought they are flying to.
That "trial flight for landing" (as it is officially stated everywhere) all think is some oxymoron, invented for political purposes, as a Russo-Polish consensus. :o) As it is a weird combination of terms.
The ground control never allowed them landing; neither the crew ever asked for the permission to land. While theoretically the crew should have informed the ground control type "we intend to land" and get "OK, landing permitted".
This exchange never took place.
What the crew got from the ground control is OK for their intention to come down to 100 metres and check visibility - with the ground control warning that "OK go to 100 but be ready to go for second circle from that point."
So, formally, the Polish crew was not landing, only going down to 100 metres to have a look. Somehow they over-did it.
Continued to 90 and 80 and further down.
Ground control told them "hundred first, horizon!" (in Russian) (sto pervy - gorizont!)
Now the Polish investigators wonder if the crew understood what the command "gorizont" means in Russian. (101 is the plane's board number, and as they heard it in Russian already several times during this very flight previously, they must have kniwn "sto pervy" means their own bopard number. Especially as it is proved the Captain knew Russian excellently well and it was the Captain himself who kept talking with the ground control. Most likely because his navigaor did NOT know Russian. or knew it far worse. while normally it'll be Navigator's task to keep talks with the ground control)
A test - would anyone here Western-trained understand what it means when a Russian control tower says sorry shouts :o) - "Gorizont!"
(hint - you as a pilot already know you've just crossed the 100 metres decision taking height) (and no, you did not request permission to land)
?