Surely the correct answer is "use some established third party library that does this exact task well". Probably faster, better battle tested against weird input, localised etc etc than anything you can come up with by yourself.

Though obviously that is then useless if the interview is actually for someone who can actually write something like this for some super secret internal thing that is nothing like the problem solved by the standard solutions available. But is that really the case? I have doubts.

If I was hiring though, I'd be more worried about hiring people who would write standard elements from scratch (mostly because that's more fun) than re-use standard building blocks to get a task done correctly.

e.g. for this specific question I'd be most impressed with someone who could talk about Spacy or some other standard library that can do a lot of things in this area very quickly but also be repurposed to do interesting new things. Do I need someone who can write Spacy from scratch or someone who can use Spacy?

Immediately optimising by ignoring non-ASCII and punctuation seems mor elike a red flag than a positive.