Al Salamu Alaykum
I traveled to another country for 8 days during Ramadan and Eid. I stayed in the same city for the whole of my trip. I shortened all my prayers and combined some of prayers throughout the whole trip and I broke my fast 4 days out of Ramadan. I have read that the period one is considered a traveler is only 4 days but allegedly some scholars like Ibn Taymiyyah and Sheikh Ibn Uthaymeen have not specified a period. Based on this , my question is, are my prayers valid and can I simply make up the fasts or do I need to do something else, like pay a kaffarah to make up the missed fasts ?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad  is His slave and Messenger.

Our view, here at Islamweb, which is the view of the majority of the scholars, is that it is not permissible to shorten the prayer and to break the fast for those who reside in a country for more than four days. However, the layman can imitate the scholars he trusts. So if you follow the views of Shaykh Al-Islam Ibn Taymiyyah and Shaykh Ibn ‘Uthaymeen regarding this matter, then there is nothing wrong in doing so. Your prayer is valid and what you did is correct, and you don't have to do anything regarding the days you didn't fast except making them up.

According to the view of the majority of the scholars, you must make up the prayers that you shortened, and you only have to make up the days that you did not fast, and you do not have to expiate for them.

Allah Knows best.