so if it was faulty code, it cost them about half a million dollars
Well, at the time it was closer to ~$160,000.
the question is: have they fixed that bug now?
Who knows. The mistake hasn't been repeated though, so presumably the miner realized their mistake and changed their code so it wouldn't happen again, although as far as I am aware no one has ever admitted it was their fault. There are still a number of pools including RSK commitments to their coinbase transactions, such as Binance, AntPool, and Poolin.