Albizia is also my guess to the identity of the tree. In USA called Mimosa. As said above, in the USA they are very invasive and disease prone trees. But you are in Romania, I do not know if Albizia has the same problems in Romania as they have in the USA. If you can keep Albizia healthy, perhaps in a more Mediterranean climate, they can be an attractive tree. The compound leaves make it difficult to use for bonsai.