The Romanian sentence can be used with derogatory meaning as well. (I mean, that if you get to know romanians, you will actually hear versions of this sentence).
Este "an" in loc de "a" pentru ca "owl" incepe cu o vicala slaba. eg. an umbrella, a university
Da, usually "an" is used instead of "a" if the next word starts with a "hard" vowel or a silent "h" - see: https://proofreadmyessay.co.uk/resources/academic-blog/an-instead-of-a/