I was under the impression that the "glass" slipper in Cinderella was a mistranslation of the French word for fur, now I find that it was, in fact, a glass slipper after all and not a mistranslation. Any light from esteemed contributors?

The English-speaking world got the story from translations of Charles Perrault. Perrault has a slipper of "verre" (glass), not "vair" (fur). There's a widespread idea that it should have been "vair", but no one seems to be able to prove this.

Snopes goes for glass. See http://www.snopes.com/language/misxlate/slippers.htm

TT my references of Perrault say it's a translation of
"pantoufle de vair" so if there's any French/english experts who can translate it!

pantoufle = slipper
vair = squirrel fur.
Comfy,n'est-ce pas?

The French "Petit Robert" dictionary calls vair a "fourrure de petit-gris" and defines a "petit-gris" as a type of squirrel found in Russia and Siberia. The "Petit Robert" describes Perrault's "Pantoufle de verre" as an unusual spelling for "Pantoufle de vair".
Vair was very expensive and became one of the "furs" used in heraldry. See: www.houseofnames.com . Giving somebody a pair of "pantoufles de vair" must have been like offering diamonds.

Charles Perrault apparently has VERRE written down so the GLASS translation is accurate, also in Perrault's time "vair" was a word no longer used so it was exceedingly unlikely that he misheard it in a story he was told and made the error from vair to verre whilst listening or writing it down.

Flem-ish - your source is arguing that Perrault didn't mean verre, actually meant vair, and either deliberately of accidentally mis-spelled it.

My source literally says:{"La pantoufle de vair" ( ou de verre, selon Perrault) dans le conte de Cendrillon.} To me that is very ambiguous.
But though vair in the meaning of "squirrel fur" has now become archaic, I doubt whether it was archaic in Perrault's time.( 1628-1703).
Googling for vair you may come across this quotation from 20th century:
"La capote, c'est le soulier de vair de notre génération. On l'enfile quand on rencontre une inconnue, etc." From www.citationsdumonde.com.

By choosing the term "unusual" I tried to be cautious.What we now call wrong spellings may have been accepted variants two centuries ago. After all attempts at creating strict rules of orthography are a relative novelty.
But I do agree that le Petit Robert probably sees Perrault's "verre" as a mis-spelled "vair". How can we know whether Perrault meant glass shoes
or fur shoes? Did his stories include illustrations?

I found an on-line version of the original text at the Document Gallica site.
[gallica.bnf.fr/scripts/ConsultationTout.exe?O=N089293&T=2] no longer exists

It shows how Perrault's orthography differs from Modern French. It does not solve the question whether he wrote "verre" meaning glass, or misspelled "vair" meaning fur. Apart from the word "verre" there is nothing in the description that suggests glass. No brittleness or light reflections suggested. The ladies in the story don't seem to have any problems with the glassy character of the slippers or shoes. It's just the size that doesn't fit for anyone except Cinderella. If Perrault really meant glass, then it may have been a poetic invention of his. His genius "reinventing" some details of the story, in this case helped by the phonetic ressemblence between "vair" and "verre". Glass suggesting purity and magic. But was it a (sub)conscious choice? He simply may have misunderstood an oral version of the existing popular story, and have been charmed by what he thought was a story about glittering glass slippers.

If he meant "vair" "fur" he must either have been a bad speller (very unlikely) or there must have been an eighteenth century orthographic variant for "vair".( Possible but not likely.) Anyway nobody mistranslated "vair" as "glass". It's Perrault himself who writes "verre". It should also be taken into account that in the oldest Chinese version of the story, it was a "golden" slipper. See
surlalunefairytales.com/cinderella/history.html [webpage no longer exists]

Golden suggests both "expensiveness" and "light-reflection". So both "vair" ( expensive ermine-like fur) and "verre" ( glitter) fit the poetic core of this fairy-tale, of which there exists an unending list of variants. Some even Native American.

The first edition of Perrault's stories contained illustrations, but I could not find out if there was any of them displaying Cendrillon/Cinderella 's "pantoufles de verre". Though Hugh Rawson in his "Devious Derivations" (1994)correctly signals that the glass slippers cannot have been born from a mistranslation from French to English, he does not really solve the riddle how "vair" became "verre". My own preferred hypothesis is that Perrault "mis-understood" the oral version of an existing folktale. But who can prove that it was not just a stroke of genius: Perrault sensing that a "glass" slipper had infinitely more poetic potential than the obsolete "fur slipper", and consciously re-shaping this detail?

Chi lo sa ? As long as philology has not decisively proved it was some sort of linguistic misunderstanding or orthographic error, there should remain room for "poetic invention" as the explanation. In that case we owe a wonderful detail to one man's creative genius. In this case not a metamorphosis of details brought about by the " anonymous folk", but by an identifiable author. Alas there is no proof, no certainty.

https://www.snopes.com/fact-check/glass-slippers