Beta v7.47.489
In the RAW ACCOUNT:*: event, the value of $1 is already written to $ial().account before the script can look up what its old value was. Could $ial().account retain the old information before it gets updated? Perhaps a ^ event prefix? Perhaps /updatenl can be used? Perhaps update $ial().account only after the event ends?
Currently there is no way to discover what the user's previous account was prior to them changing accounts.