Did you catch the part about self-induced fluctuations? Somewhat like self-induction in electronics. In this idea, the inflaton field (being a scalar field, like the Higgs field) self-induces what they call 'low roll inflation'; this happens of its own accord. Similarly, the Higgs field tugs away at energy, giving it mass. The inflaton field doesn't have to have a beginning or end (which fits the idea that inflation never stopped, it just slowed WAY down); It's the 'let there be light' moment.
The nature of the inflaton field is that of pure massless energy, just waiting for the right self-induction to happen.
If you think that the multi-verse is on the right track, then one way for it to happen is this see-saw idea. In it, a Universe's black hole's singularity (which is the end of matter for THAT universe) dumps into a new Universe's white hole singularity. It's not that this idea doesn't explain ANYTHING; it does fit several ideas about singularities and white holes, but there are other violations to the idea.
I'm not versed enough to say whether theses violations prove the idea is a dead end (sometimes there's an epiphany that changes everything in Physics), but it is an idea. A ping pong idea, yes, but that alone doesn't rule it out.
Your extra-dimensional collision idea sounds very much like m-brane theory; positing that two 'branes' came into contact and sprouted the Universe. I tend to like that idea as well, although most of it is based on unobservable ideas (currently unobservable I should say); the math is very elegant though.
Yes, there's a glass ceiling in there somewhere; some questions don't have meaningful answers. I suppose the quest is to get our noses right up against the ceiling to see if we can see anything beyond it; even if its blurry and makes no sense.
Headlines about ANYTHING are always disappointing; the words allude to something, but the text is filled with caveats and sometimes reversals; That's not limited to talk about physics. I don't read anything with the presumption that 'scientists are trying to sound as if the universe is a solved puzzle', as you say. I don't expect that, and I don't read that into what I hear.
The thing I liked about this inflaton field theory is PRECISELY that it abandons the 'chicken-egg' questions and 'particle zoo' theories. It separates itself from the standard model
There are two typical responses from a physicists psyche. They tend to either become more aqnostic or more 'pro'gnostic (?) IOW they believe that it's all a bunch of sterile and random shit, or there's an intelligence behind it (in some form). Not all scientists can be rolled into that pigenhole, You brought up cause and effect; You'll LOVE the next video then (bringing up the issue of causality, why the arrow of time marches to causality's drum, and how it can be reversed).
I don't think that Hawking came up with the idea of vacuum fluctuations, and I disagree that we all know that scientists don't like the idea. Inflation theory suggests that the tug of virtual particles in otherwise empty space is responsible for the hubble constant. Quantum tunneling, (a known phenomenon that happens, for example, inside simple transistors) depends on virtual particles.
That's a neat thing about this inflaton theory; it recognizes the fact that only unobservable assumptions can be had when staring at a blank wall (the universe was opaque to light when it was so tiny and dense, so nothing can be seen of its beginning).
This idea abandons all that trying to peer through the CMB; it accepts that the 'big bang' standard model can only be walked back to a certain point before it gives no more traction, and it approaches the known conditions it tries to model from the other direction.