Would be interesting to have a translation rating aside of the novel one, i've seem before people that seem to lower their ratings based on translation and a bad translation also have an impact on understanding some novels
Honestly, I understand why someone would want this. However, as NU ain't hosting the novels, I feel we shouldn't have it. It makes sense for a professional place like WW or QI to have this feature. NU is for fan groups, just as it is for TLs looking to earn.
Not gonna happen, it does nothing to the story other than discuraging its current translator when they receive bad ratngs. Also, this kind of rating becomes kinda useless when you realize a story can have multiple translators. Not to mention readers aren't qualified to judge translation quality. All you can do is judge the English level of the translator. This was already suggested before, it is pointless to ask for it again.
But you know, NU does have quite a big selections of groups. From a regular member's point of view, where else do you think is appropriate to have the groups and translators rated aside from NU? Of course, this won't be implemented, at least not without good reason and motivation from the lizard king, as @AliceShiki mentioned: So let's dream for a bit and imagine this is implemented. With the current layout that NU has for the Group page, instead of an overall rating, their quality would be rated based on the novels they have listed on their group page. So when a visitor go to a Translator's group page and check the series they're doing, they will also see the TL rating for the novel maybe somewhere near the titles, such as "(3.5) Title". As for how members are going to rate them, on the novel page at group filtering button above the chapter list, the groups who does translations for the novel will be listed. So a Rate/Rated would appear next to those groups that'll allow the member to rate the group. Of course, to avoid the hassle of having to check the rating at group page, the group list should also appear with the current rating the group has at the time somewhere near them. Again, it's a dream. It's a possible situation but due to many reasons (rating manipulation, discouraging translators, public shaming etc) this most probably won't be implemented. It was a nice thought to have but it can be harsh to the growth of the community and NU.