This comes from personal experience. I own a block just up the road from this property and had the same noise condition imposed upon my development. In my case the DA was for a PPOR house. We received approval in the first week of January this year.
In order to comply with the noise condition, upgrades to the building elements would have cost in the vicinity of $150,000 on top of standard type construction. This extra cost would have have meant we couldn't proceed with construction.
The good news is, as I've only just found out, that it is possible to get the noise condition removed. Under Qld's Sustainable Planning Act section 345, any development conditions are required to be 'reasonable'.
We made 2 submissions to the Qld Government Department of Planning to get the noise condition removed from our development approval. We were not happy with the revised noise condition in response to our first submission so we tried again. The second time around we were successful in having the noise condition completely removed.
The whole process was a massive pain to go through and was quite costly - involving multiple acoustic reports, as well as the additional holding costs and rent during the process.
Given the process involved in getting the noise condition removed, I wouldn't recommend buying on or within 25m of a railway line in Qld - especially when you are constraint to Character Code requirements as well.