4th red cable to A - COM - L1
and yellow-green to B - 2way - L3
L1 and L3 on this side were also connected with a short red cable. (so red and g&y were bridged with a short red)
I've put some red and green lines on the photo exactly as cables were connected (G&Y cable marked as greenish).
I'm trying to make sense of the wiring of the switch (after my niece bought a house 2 days later one of the switches stopped moving properly and tripped the fuse).
An electric lamp switch with two buttons - one button broke. I'm pretty sure it's not 2-way, but two separate bulbs, one for one...