When leading international projects, culture is usually a block, which is preprogrammed behaviour on the workplace mostly influenced by the leadership at that place “unwritten rules”. This is ecspecially true in Europe where culture is much more diverse then in USA for example or among the nordic countries that have similiar culture.
There are many ways to do this, usually best outcome is to involve all parties and find some shared values and benchmark the best process. HR function most be involved in this, change need to be facilitated not coached, coaching is manipulation. Facilitate change like conducting an orchestra.
Great leader have strong focus, understands everyone and focus on shared goals and values.
On the top of the iceberg there is much differences so much that someone could thing this is impossible, but when go deeper, can see that all come from same source, they have shared values.
In the beginning it is very important of course to have clear goals but also to set up a process and shared values for the project. It is also important to focus on success, visualize that success and be on time also, follow up often. Projects have tendancy to take too much time. It is better to have a little pressure.
Also have agile mindset, learn, experiment and analyse, if something goes wrong be quick to transform the process.
Love what you are doing, have fun and believe it will be for the greatest good.
Bjorg in Reykjavik Iceland