So for 1/2 past the hour, the literal understanding is "1/2 of 1" but then "1/2 of (the) 2nd/3rd/4th" etc?
It is half TO, but otherwise you are correct.
půl jedné = 12:30
půl druhé = 13:30
půl třetí = 14:30
So indeed, not první, but jedné.
I think that's also correct answer: "Is it really half to four?"
No. Not in English
"Is it actually half past three?" Not accepted?
No report from you in the system though. Please do report when you believe you are correct.
Here we do not accept "actually" yet. Should we?
I think "really" would be used much more often, at least in the US, but "actually" could also be used. (Would "opravdu" vs. "vlastně" be a factor?)
What about "verily"? (someone complaining abut "truly" already..)
Yea, verily, "verily" could be fun... (sorry).
In Shakespeare' time verily