"How is the nationality of the lecturer (w/ a diploma) a relevant fact?" -If you are not familiar with the issues here I can't be that helpful.
The quality of academic institutions and systems varies widely on a nation by nation basis. This is the issue I guess, a site like this and you are claiming no difference between countries.
Note that many top US scientists come from other countries, so its not the nationality of the scientist that is critical but the system they operate within, and the issues with academic integrity in China, Africa and yes, Romania are reasonably well known. Even the US and UK have struggled, and have tons more resources (some struggles relate to their overseas programs).
Hiring your own graduates is sometimes considered a bit of a weak sign in academia as well.
It's the totality of all these factors, bogus "endorsements" by big name media orgs (BBC), medical doctor endorsements from overseas doctors that practice relatively niche medicine (cannabis practice), and scientific research that seems to take any paper written anywhere and treat it equally.