I had this exact topic with an Irish coworker who lives in Germany and has issues to convey the right time. For me as a German „half one“ is half of one so 12:30. Same for „Dreiviertel eins“ -> „threequarter one“ being 12:45 and „Viertel eins“ -> „quarter one“ being 12:15. To be fair the logic behind this is also under constant confusion as some parts of Germany rather use „viertel vor“ or „viertel nach“ -> „quarter to“ „quarter after“ and have no understanding of the three quarter business.

In the UK yes, I think not in AmE? At least I'm pretty sure they don't say 'quarter to' or 'quarter past', and do say 'a half after'.

(I had some confused conversation with a bus driver once. Bizarre experience to have so much language barrier between two EFL speakers, in English!)

The Irish like to say "half one" meaning "half past one". In my native timekeeping parlance "half een" means 12h30. Germanic/Dutch origin.

So whenever I talk time with the locals here I repeat the time back in numerical style to avoid confusion.

"The shop opens tomorrow at half ten".

"Thanks, store opens at nine thirty. See you then."

"No..."