I've never really minded san/sama (as long as it isn't overused), but I've always had an issue with the "big brother" translation. No one calls their big bother -> Big Brother. You call them by their effin name.
Depend, it can be the case with very young kids even in Western countries but for adults, it's clearly never happen or it's very rare.
I don't like to see -san -chan -sama and such kept but the big bro doesn't bug me that much, as it's sometimes hard to put the name, especially if this name is near never used (in a anime for example), as they near always use the family name and so seems completely off.
The problem with Japan -> English/French translators is that they are quite rare, and so we "take what we have", even if they don't have good skills in their own languages. I'm lucky : I worked with 2 translators (Hiei- and Eien Ni Hen), and both of them did a marvellous job (go play Phantasy Star Generations 2 and Psy-O-Blade if you don't believe me), but I've played French translations so badly written that I switched to the English one : at least, if they were bad written, my English was not good enough for me to notice
French translations are pretty good since a few years ago. For example, if you try the Earthbound or Mother 3 translations, you can see they feel pretty nice. But I'm okay with you for translations which was made like ten years ago, they were often done from english (and english ones weren't also pretty good 10-15 years ago) and the biggest problem at that time was how to fit all the texts in the game, which were often fixed by cutting some texts, like the old official translations.
The general rule I noticed is "the more texts the game have, the better the translation might be" as bad translations I saw are often for games with a few texts (NES games for example) that everyone can hack/translate. When it's a game with a lot of texts, it's often mean "a big/deeper hack" so the size of the translated texts are rarely a problem, which often give a far better translation. I did some old translations back in the day, before I learnt japanese, and you often had to keep a specific size for the texts, so you were forced to cut some lines and remove some of the dialogue contents (It's also what happened to the official french translation of Secret of Mana. The translation doesn't look that bad for a 20 years one but when you compare it with the japanese version, it feel like 2/3 of the dialogues were cut to fit in the rom, probably to spare some money and avoid using a 32M cartridge, as Secret of Mana is a 24M one).
And, of course, if it's a translation made from english, the english one should be good or else it'll also impact the french translation. But I'm one of those who think it's better to translate a game from a good english translation rather than translating directly from japanese with some limited knowledge of the language.
Japanese to English translators are a lot more common than Japanese to French translators, unfortunately for the french romhack community. I guess I know most people from the french romhack community and I don't think I'm wrong when I say that I saw less than ten Japanese to French translators in the whole community during the last 15 years.