Thanks! I've been teaching English here in Brazil for the last few years, and this pronunciation issue is quite fun to watch. It's language 'erupting', in a way.

Which "o" are you trying to find a symbol for? The "o" in "harmonica" (which is /ɒ/) or the "o" in "Omen"? The "o" in Omen, in English, is always a diphtong, so you'll always find it as /oʊ / (or with a schwa, /əʊ/. (The schwa /ə/ is the weakest vowel in English, and it's kinda hard to explain the sound of that diphtong over there, but think of the sound of 'a' in 'about' together with a /ʊ/ sound.) The IPA for Japanese shows the 'o' sound in 'oniisan'. Is that what you were looking for?

Like I said, the /ɔ/ is generally not found outside British English (and/or Australian and NZ English, with some variations). So I probably meant /oʊ/ or /əʊ/ or /ɒ/ (like explained above)

That is the difference I found between Jesus' explanation of how he meant the word to be pronounced (exactly like you transcribed, considering that's how he would pronounce "Monica") and the way I heard it pronounced in qgil's address, /ma'ɛ:mo/ (or /ma'ɛ:məʊ/ as most English native speakers will almost definitely pronounce it).

(However, I couldn't find the word "maemo" in the other presentation he linked here, from Ari Jaaksi. If he could point it out I'd be grateful.)

And that's where the confusion still stands =)