Belgium 1958 50 Francs with designer's inscription? [solved]

I came across this coin with nicely carved inscription on the reverse.
The signature of this inscription seems to be done by the designer of the coin.
However, I'm not good at reading hand-written words at all.
And English is the only European language I can read.
I have tried to guess each alphabet but the translation from Google made not much sense except telling it may be French.
Could any one tell me what does it mean, please?
And is this inscription really scripted by the designer of this coin?
Any help would be greatly appreciated.
I can take much more detailed pictures if needed.

pour Mr ? l'auteur [engraving]
for Mister ? the author {French translation]

https://en.numista.com/catalogue/pieces6459.html [French text]
https://en.numista.com/catalogue/pieces6460.html [Dutch text]

It is the first of those two coins. So French engraving on a French language coin.
The engraving is post-mint damage, and was added later. You can see
on those links it is not on the original coin.

I think it is 'pour Mr. Gueldre' , which is a not uncommon surname,
signed by the author.
That's a nice item. I wonder how many of the coins he autographed.

Yes, that looks like it.

pour Mr Gueldre - l'auteur C van D [engraving]
for Mister Gueldre - the author C van D [French translation]

Then on those links I now see it is the coin engraver's name after the inscription >
Engraver: Carlos van Dionant de Cacérès
and presumably this was done at the commemorated event - Brussels World Fair 1958.

A nice find !

The lettering is something like this >

Quote: "Mr. Midnight"​I think it is 'pour Mr. Gueldre' , which is a not uncommon surname,
​signed by the author.
​That's a nice item. I wonder how many of the coins he autographed.
​
​
​
​

​Thank you very much for your answer.
In fact "Gueldre" is the first word I recognized. Since Google told me Gueldre is Gelderland in French, I thought it must have something related to the Dutch province and went a wrong way to investigate it, wondering why it is the French version.
And as I searched. It is the only sample engraved by C.V.D. So I'm very happy to have something special.

Quote: "ZacUK"​ Yes, that looks like it.
​
​pour Mr Gueldre - l'auteur C van D [engraving]
​for Mister Gueldre - the author C van D [French translation]
​
​ Then on those links I now see it is the coin engraver's name after the inscription >
​Engraver: Carlos van Dionant de Cacérès
​ and presumably this was done at the commemorated event - Brussels World Fair 1958.
​
​ A nice find !

​Thank you very much for your kind answer. Because of the spacing of each word, I thought it might be "​pour Mr Gueldre l'auteur - C van D".
I tried to translate it with Google and searched for "the author" of "Gueldre" but had no luck.
Although "Mr Gueldre" was probably a friend of the engraver as I could not find any famous people named Gueldre. And there is no any evidence to ensure it was done at Brussels World Fair 1958. As long as the inscription was nicely engraved, I love it so much because it is a piece of beautiful handcraft together with the coin itself.

True, there is no evidence, (we haven't any yet) but it makes a good story.

edit to add: I am now searching for the story and another example of the autograph.

Quote: "Mr. Midnight"​I am now searching for the story and another example of the autograph.

​It is great! Please share what you find. That would be an interesting episode.