Javad, I applaud your research and your efforts! It's an unusual husband that will go to all that work to ensure his baby has the perfect name!
I'm going to give this a go...apologize in advance if these are unusable, I'm completely unfamiliar with Chinese.
Oisin (o-SHEEN; You Xin) - Irish for "little deer", a Celtic hero from the epic Tir na nOg
Lucien / Lucian (LOO-shun or LOO-see-ahn; Lu Xun or Lu Xi Yan) - French / Latin meaning "light"
Milan (MEE-lahn; Ming? or Mei? Lan) - Sanskrit meaning "unification, union, or coming together" which I love, since you're striving for unity on this name decision. Also a city in Italy, means "kind, loving, and gracious" in Slavic and "eager, laborious" in Ancient Roman
Kishan (ki-SHAHN; Ke Shan) - a modern form of Krishna, meaning "black, dark" in Sanskrit
Matthias (muh-THY-us; Ma Tai) - Matteo, Matthias, etc are all variants of Matthew, which means "gift of God" in Hebrew
Caius nn Cai (KYE-us nn KYE; Kai) - I love Kai. It's Hawaiian for ocean, similar to your wife's favorite, and Caius would be a great way to bring in the ancient Roman sound. Caius means happy. There's also Malachi as a way to get to Kai...you could even do Ma Li Kai which is slightly different pronunciation, but still really close. Malachi is one of my favorite names...it means "my messenger" or "my angel"
I can see your dilemma!! This is really difficult, I've been browsing for a good while now and only have a paltry seven names to suggest :(