Attending a specific group activity eases the pressure of making friends, by giving the child a reason for being part of the group. It will also boost their confidence, encourage them to find positive aspects of the country and teach them, through host country friends, how to make the most of the country that is now home. A major cause of stress in a foreign country is the inability to understand what is being said and written. This lack of language skills can also make it more difficult to appreciate how to successfully live in a country. If the local language is not being taught in the child's school, consider private lessons.
Younger children pick up a language by assimilation.
If you have local friends ask them to speak to young children in the local language, especially if you expect to be in the country for a few years. Continuous exposure to the language will help the child learn it and make their stay in the country much less frustrating and much more enjoyable. The effects of culture shock usually fade over time, especially with family support and encouragement to understand the differences met during time spent in a foreign country. The time scale of this pattern varies for everyone and not everyone experiences all three. The most common time scale seems to be approximately a week of Euphoria, a couple of months of Depression and many months of Adaptation.