Let there be new heroes, but the old ones should be mentioned as the great warriors of the past!

That's a good point; the plot doesn't really connect with the old one; only the name "Griffin Empire" remains.
I have the impression that the developers glanced at the fourth game, took some ideas from it, and then forgot about its existence. In fact, they could build a continuation of the plot: Much time has passed since the days of the Great Heroes; the former glory of the Griffin Empire during the times of Catherine and Roland has been lost, and so on.
In general, I am already interested in what will be in the sixth part, if it will be made. There is room for improvement, but I agree that the history should not be forgotten.

Added 3 minutes later

Mugais;88041

That's why I also think that the third part is the best.

The fifth... You won't believe it, but I can't force myself to play it more than a couple of times a month...