Staying abroad made me realize my poor understanding of Japan for the first time.
としてもいいですか？
私的には、staying abroadがある程度の期間を表すのに対し、for the first timeがある過去の一時点を表すのでおかしいような気もしますが。
Now that I have started living in another country, I have come to realize there are a lot of things I don't know about my own country.
ーNow that I have started living in another country, I have come to realize there are a lot of things I don't know about my own country.
「海外で暮らし始めて、自分の国について多くのことを知らないことに気がついた」
to live in another country で「海外で暮らす」
to come to realize で「〜に気づく」
ーNow that I'm living abroad, I have come to the realization that I don't know as much as I thought I did about Japan.
「海外に住む今、日本について思っていたほど知らないことに気がついた」
to live abroad で「海外に住む」
to come to the realization で「〜ということに気がつく」
don't know as much as I thought I did で「私が思ったほど知らない」
ご参考まで！
カナダ 
