Would it be possible to "create" a new World Rune?

From how I understand it, the world runes are kinda relicts from the creation process of the world. They embody elementary concepts of existence - for example there might be a rune that means "space", another that means "fire" (hello there, living puppet of a possibly sentinent rune ), then another could mean "time", and so on and so on. I'm also sure one of them also means "gravity", that I suspect materialized inside of at a young age (would explain her limitless powers that appear gravity-focussed.).

Now these runes are apparently indestructible - and even if you managed to break them, they would just manifest somewhere else. That's not simple durability, but being bound to existence itself.

However, runes are also letters. For one that means letters can be arranged into words and words into sentences. Meaning that you can use runes in combination to create an effect that is more than the sum of its parts. My personal theory is that when you get absolutely ALL the runes, you can re-create the universe. This is pretty much Riot's version of Marvel's Infinity Gauntlet, a tool that has to be put together first, but that provides the wielder with gigantic power beyond comprehension.

But letters can also be changed, and one can also invent new letters. Like, take the ancient latin alphabet. It for example had no Ä, Ö, or Ü that are now present in the german language that uses an alphabet based on the latin one. It also had no J either and no differenciation between U and V. And no W either. These were all letters that just came to be later as the language evolved.

So if runes are letters and words, what does stop me from "inventing" a new one? Even if it is just a slight change to a pre-existing one?

And given the power potential of these runes that would have some serious consequences. A small nation getting control over world-rune-power is pretty much equal with them suddenly having a nuclear weapon arsenal. Simply it existing caused trouble on the international stage, see the whole mess around North Korea for reference.