If in a 51% attack transactions can be reversed, isn't it possible that the chain with more hash rate also changes transactions (for example if x sent 5 btc to y, they would change it to x sent 500 btc to y) and then would confirm such malicious transactions more often than the corresponding good transactions that were confirmed on the honest chain.
I have this notion that transactions get n number of confirmations if after the block with that transaction was added, n more blocks were added.