Actually neither my version nor yours had this error.

The key issue here is that you cant just replace .{BS} with // as this allows other char sequences to "become" a {BS} element. The process of converting {BS} to a \b char and _then_ converting the .\b's resolves this issue.

But you are correct that ultimately there is no way to recover what was actually _entered_ into the computer without knowing the input rules that applied at the time of entry. Basically IMO this entire task is an interesting game but ultimately a futile one from the POV of actually solving the problem.

Yves / DeMerphq
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Software Engineering is Programming when you can't. -- E. W. Dijkstra (RIP)