It's an awkward position to be in, but I reckon (American) English-speaking manga readers are becoming increasingly sensitive about translations that aren't straightforward because American localizers-- corporate and unofficial-- have a nasty habit of not doing their job and sometimes outright voicing contempt for their consumers. They play creative and reinvent the script for their own palates, using the excuse that they're doing it for the sake of "western audiences" or the "modern era". Technically, this has been an issue ever since we started importing media from Japan, but it's reached comical and mean-spirited heights only recently.
Pretty much all official translations from Japanese to English, and in reverse by the way, are completely re-invented but no one gets angry. How would they know when in the case of books, they can't see the original, and in the case of subtitles they can't understand the original lines? The things people get angry about are the really basic things they think they know without understanding Japanese. Anyone who does know Japanese is used to it and doesn't get angry, because he knows it's a complete mountain of completely re-invented scripts and every other line omits things for no reason, inserts things that weren't there or simply uses far stronger or lighter words than what the original uses or alters what they're saying to make things time better with the subtitles.
Fan-translations tend to stick more to the script, but they also often give a wrong impression of the original lines with it. The kind of translations that literally copy the word order and use dictionary definitions, not realizing that word order plays a different function in both languages, and that the dictionary definition is often outdated or was never accurate. I've done it many times myself too and hit myself over the head later, quite recently even when I translated “争い” to “conflict” and it's usually used for a conflict or a battle but there was something off about that line but I just let it be but just after I uploaded it it hit me what was wrong about it and I actually looked it up in a dictionary and it gave “struggle” as an alternative translation. I should have used that by all means. The problem is that the English word “conflict” implies that both sides have volition and a will, whereas “struggle” can be against nature, or against one's own emotional problems and this was definitely a “struggle”, not a “conflict”. — It's a mistake, but it's there now.
The best most of us can do is jump at nonstandard translation choices
On the assumption that the standard is “right”.
I will say one thing very simply and clearly here: I'd be suspicious of any translation of Japanese that has all teenage characters speak in standard, non-slangy English. It's extremely rare for this to be the case in Japanese.
Anyway, the takeaway is that if people want to complain about lack of accuracy they have a big mountain to climb. People say they want accuracy but why would it even matter when they don't notice and given how much they don't care about all the extreme inaccuracy in translations from Japanese, I don't think they care as much as they say they do.
For what it's worth, I trust people who are willing to provide translation notes-- to talk less of not completely effacing the original JP text. In your case, the dialectal British English (and the really arguable renderings of honorifics and titles) is a small price to pay to see and comprehend comics about young cows eating old grass.
Probably a better indication yes. If translators are willing to provide a note at the end about what was lost in translation or note that a particular word they used didn't quite capture the meaning, but they couldn't think of a way to do it better, they're probably invested into being accurate.
But really, what does it matter anyway whether it be accurate to the reader who will never really find out?
