Yes you can't expect that they will be world class, so you can use the money for better signings, and not take such cheap players.
Who the hell was Duarte? A defender who did not convince Flamengo fans
Saelemaekers was also not good in Belgium
Rade fucking Krunic, a 25 year old who got only one full season with Empoli.
Did it occur to you that sometimes you need to cover 3 positions and better players cost as much as your whole budget?
Buying players like Krunic and Duarte is not a problem, all midtable/pre-top clubs do it. We are not Real to buy 2 best players on every position.
As for Duarte, why would anyone care what fans think? Look at this forum, even Romagnoli has his own little haters . Many so called fans don't watch matches, only youtube videos.
I remember Duarte was rated highly. Don't know what happened between him and fans, he could just have bad season