I find equating 'oblivious' with 'unbeirrt' rather inappropriate.
Oblivious = 'not aware of' (that may include 'has forgotten' about something)
'beirrt' means 'led astray / mislead' – the part 'irr' translates to 'off the path' / 'astray' / 'crazy' / 'chaotic' – so, 'beirrt' suggests external, likely behaviour-changing influence.
The simple antonym 'unbeirrt' translates to something like 'steadfast' or 'knows the way' – it's in the neighbourhood of 'unwavering' and consorts (right?). And although it is occasionally used negatively, turned into its opposite, to suggest inappropriate stubbornness, obliviousness or worse (example: "sie pflanzen sich unbeirrt fort"), that's not what it really means.
The word absolutely translates to = Unbecrazied! / "not having been made crazy". Or, 'sane'.
Not saying a steadfast person can't be oblivious. But a false translation like the one suggested does exactly the opposite of that (and thus the same thing), implying that someone unbeirrt is necessarily oblivious. Which is ignorant. Which disqualifies it from aptitude