those Ilyushins had a very bad design fault
Crashes can and do happen for many reasons. Even on the best designed aeroplane.
many places in built-up areas
Generally people try to avoid having aeroplanes approaching airports over them. Or building airports close to a city centre. It's handy for passengers, but too near.
With Sydney, the flight path in and out is carefully chosen and construction is heavily restricted.
This thread is about train fares though, not airports. The rail link to Okecie does work though isn't as popular as was hoped. If Modlin is to work in the future, as well as enlargement, they will need to improve rail. It isn't the fares that are the problem it is the waiting.
Mszczonow was an ideal,place. It would need a new station and that could be incorporated into the ticketing zones. A special airport ticket is not unusual.