Ok, maybe unnecessary post because I managed to solve it in a way I am satisfied with and in a way that shouldn't cause any overfill.
In the end I actually used the idea described in the post that I thought of while writing it, and that it connecting train content together with buffer and input it ...

Hi all!

Decided to learn basics of circuits by designing somewhat of a LTN in Vanilla, hugely inspired by player Ellipticality. But the problem appeared with erasing memory and "unloading delay" at a buffer station, I will explain a bit how the current system works: (I'm honestly struggling so ...