I also posted on uservoice too.
I think it is a bug, and this seems to be happening since some months ago.
When I type email title in subject field in Korean, and change focus, text I typed in disappears.
Plus, even when I typing in body filed, cursor bar blinks very unnaturally.
It is a huge bug and very critical to me, as I use outlook on my Mac everyday.
If someone is capable of typing in 2byte characters - Korean, Japanese, Chinese.. - please test it, and if you have that problem, please vote on uservoice.