An experiment with phonetic writing

[ololololo]

Isn't the premise of this that the french person would potentially understand the word once re-spoken by the person transcribing?

It’s strange that you’re stopping at this after I’ve confirmed it. Yes, a Frenchman will understand this person if he says “aujourd’hui,” and he will understand this person if he reads it in his letter. But he might not understand what he wrote.
By analogy with Russian: There is the word “Солнце”. It is pronounced almost like “Сонце”, but some people might hear the sound “a” in the last unstressed letter and write it as “Сонца”, or even “Сонц”.
How quickly can I recognize that Сонц = Солнце? Well, maybe quickly, because if you write Russian with some mistakes, it will still be understandable. As far as I know, French can be made completely unreadable with these mistakes.