Will I be able to track progress of my referrals when transferring between regions?
After some deeper digging into the league-of-hard-to-find-FAQs I found this article.
It states: You will keep your referrals but if they are on a different server you won't see the level. This also means if you or a referred friend will switch servers, he will only count towards your progress if he hits level 10 while you are on the same server.
You won't be able to see the Level of Referrals on other servers.
Here you can find the information about the things that will transfer and the ones that won't.