Silat is one of the few people that have been against Guts' full might and survived, he hates him... but he too respects the hell out of his strength, seeing him like that must be grating.
Filling the gaps is a twopronged sword.
For one, the notes likely would've been expanded if they were done by Miura himself most likely. For the other, putting his interpretations into it could result into it becoming more fanfic like, see the game of thrones show or opm with the artist. Here they prefer to err on the side off caution, given how much they respect him.
Yeah, there is no way to posthumously complete an author's work the way the author wanted, the creative process is not linear, one may plan the beats of the story before hand, have everything lined up... and at the moment of putting ink to paper, they change everything, or use those plans as no more than guidelines.
Mori-sensei took the thankless job of finishing his friend's story, because he is probably one of the few people that know what Miura-sensei had planned, he himself is an accomplished author and he has the team that Miura trained and refined for years... but there is a limit.
Personaly, I accept it, I have come to therms that the "perfect" Miura's Berserk is no more, but this is like a funeral procession for him, done by his friends and colleagues, if it was a stand alone story they would be doing a flawless job, but they can only do so much, and I appreciate what they are doing because in the end... they are doing this for the fans as much as they are doing it for Miura-sensei.