Some years ago I worked as a part-time French to English technical translator in such fields as the gas industry. This was pretty boring but these are the easiest kind of translations to make because idioms don't come into it much and there is usually little doubt about which word to use: technical dictionaries (and there is one or more for even the most recondite specialities) are very precise. Once you get into the swing of it you can zip off several hundred words an hour: argent gagné for old rope.
But literary translation, the sort of thing Céline does, is quite a different matter. Last May I posted a French limerick (or maybe THE French limerick - no-one could find me another), and recently I spent a sleepless night trying to translate it, probably averaging about ten words an hour.
I got there in the end, around dawn, and was not displeased with the final version.
However, I shall not publish it because some of my readers might be devout (though I doubt it) and would be offended by its impiety. Anyone who really wants to see it can email me.
For another French limerick see HERE.