I think “ghastly” is a bit strong. I compared an expensive translation of a paragraph of “Les Mis” with a ChatGPT translation. I found the latter quite acceptable even if the odd American spelling crept in. I am sure this could be allowed for by specifying the translation in UK English. What do you think?
Original
Quoique ce détail ne touche en aucune manière au fond même de ce quenous avons à raconter, il n’est peut-être pas inutile, ne fût-ce que pour être exact en tout, d’indiquer ici les bruits et les propos qui avaient couru sur son compte au moment où il était arrivé dans le diocèse. Vrai ou faux, ce qu’on dit des hommes tient souvent autant de place dans leur vie et surtout dans leur destinée que ce qu’ils font. M. Myriel était fils d’un conseiller au parlement d’Aix; noblesse de robe. On contait de lui que son père, le réservant pour hériter de sa charge, l’avait marié de fort bonne heure, à dix-huit ou vingt ans, suivant un usage assez répandu dans les familles parlementaires. Charles Myriel, nonobstant ce mariage, avait, disait-on, beaucoup fait parler de lui. Il était bien fait de sa personne, quoique d’assez petite taille, élégant, gracieux, spirituel; toute la première partie de sa vie avait été donnée au monde et aux galanteries.
Paid translation
Although this detail has no connection whatever with the real substance of what we are about to relate, it will not be superfluous, if merely for the sake of exactness in all points, to mention here the various rumours and remarks which had been in circulation about him from the very moment when he arrived in the diocese. True or false, that which is said of men often occupies as important a place in their lives, and above all in their destinies, as that which they do. M. Myriel was the son of a councillor of the Parliament of Aix; hence he belonged to the nobility of the bar. It was said that his father, destining him to be the heir of his own post, had married him at a very early age, eighteen or twenty, in accordance with a custom which is rather widely prevalent in parliamentary families. In spite of this marriage, however, it was said that Charles Myriel created a great deal of talk. He was well formed, though rather short in stature, elegant, graceful, intelligent; the whole of the first portion of his life had been devoted to the world and to gallantry.
ChatGPT
Although this detail in no way touches upon the very substance of what we have to relate, it may not be useless—if only for the sake of exactness—to mention here the rumours and talk that circulated about him at the time of his arrival in the diocese. True or false, what is said of men often occupies as much space in their lives, and especially in their destinies, as what they actually do. Monsieur Myriel was the son of a counsellor in the parliament of Aix—noblesse de robe. It was told of him that his father, reserving him to inherit his office, had married him off very early, at eighteen or twenty years of age, according to a custom rather widespread among parliamentary families. Charles Myriel, notwithstanding this marriage, was said to have made quite a stir. He was well made in person, though of rather small stature, elegant, gracious, witty; the whole first part of his life had been devoted to society and gallantry.