Adoption i imagine is very much done on a case by case basis and so as long as it wont be considered too much of a culture shock, it wont be as difficult to adopt. So if the child is very young, i think your chances of adoption are higher than say a child who is 8 or 9 because your wife is Romanian.
This is just me guessing though.
My girlfriends mother was adopted and has 4 other adopted borthers/sister. I have met them and they seem so so much closer than my non adopted triplet siblings.
In general it is actually much easier to adopt older Children no matter who you are for the simple reason that most people want a baby leaving older children stuck in our care system facing the generally dismal outcomes that it delivers. I have a a lot of respect for anyone adopts and even more so for someone who adopts an older child and all the baggage that can come with it