As much as we'd like certain mangas to be translated, people do this on their own time and based on their desires. Even for a business or job, someone can for the most part choose their clients as long as their business is sustainable or achieves its purpose (anti-discrimination laws are in place with generally good and sometimes bad intentions/enforcement). Readers can also choose what they want to consume. Unless it's awful, another translation is another way to interpret the media in front of us, which may or may not provide additional insight. If it's similar? That's fine too.
Rules, etiquette, and norms are in place to provide an environment and structure where things can happen. They an be followed or can be ignored/broken; either way you have to deal with the consequences of that choice. Others will have their reactions; you can choose and have control over your reaction. Happy with things? Great. Annoyed or stressed about it? Ignore or deal with it as needed. All of the above or not sure? Discuss it (that's partly why you're here, isn't it?). The real question: is someone or something getting harmed by this action? If yes, reread this paragraph. If no, then whatever.
There are artists out there that make great manga, film, paintings, etc. but are terrible people in real life. Do we consume or appreciate their art? Depends on how you feel. Do we promote or financially support it? Again, depends on how you feel/who benefits from it. Is it still worth evaluating/interpreting through the lens of what we know about the artist? Maybe. Might others make these decisions for us? Sometimes.