How risky is it to adopt a child from europe?

It isn't. In my experience parents adopting from anywhere do get a lot of information about the child and informed decisions can be made if it is a good fit for you. Family history may be sketchy, but you can get lots of information from the foster parents and orphanages..This helps you see the child's development and or emotional development. They usually provide labs that let you know health status too.
Very risky ex Russia. Unfortunately, almost all adopted children from russia were exposed to alcohol prenatally & thus born brain damaged & may also apply to other children from europe. Such a shame they are so cute as babies. This medical history is invariably lacking. Suggest read "damaged angels" by bonnie buxton. Personally have found almost all kids adopted from russia are "damaged". Beware fetal alcohol syndrome!