Is creating a journal/notebook with 2 pages and random text lengh actually impossible?

Hey,
I know everything is possible, but this one looks pretty simple, and yet, I just cannot do it.

Basically, you have this kind of set up that represents two pages (W_journalPageLeft/Right is just a widget that contains a single Vertical Box), and then you have an array of 10 texts:

You loop on those texts, and, for each, create a W_entry which is added to the left page.
If the current W_entry would go out of bounds, then add it on the right page instead.

It should be so simple. The algorithm is easy. But getting the correct value is a nightmare. I had so many troubles, like when/how to use delayUntilNextFrame, or ForceLayoutPrepass, or a mixed of both, get desiredSize, or GetCachedGeometry->GetLocalSize?
I even had some crazy stuff like, when adding delayUntilNextFrame inside the loop, some Bp were just skipped.
And later on, adding a breakpoint and going through each node would run the code. If no breakpoint, absolutely nothing would happen (probably because going trough a breakpoint will go the the next frame so the UI will be created, but still crazy to think about it).

Any idea about this? I am so lost over such a basic stuff.