To answer the general question - yeah, it's definitely a team effort. Each game gets one translator and one editor, and together they work through the script, decide name spellings and key terms, all that stuff. We then sit down and do a script party with the rest of the localization staff, where we read through the entire script to solidify tone, style, terminology, all that stuff. For the most part, translation decisions are left up to the translator/editor team, but if there are any big changes/choices, we'll discuss it as a team. And of course the game title/subtitle gets decided as a team, as well.
In the example you mentioned for
the translator and I discussed the possibility of a change, the pros and cons, and we decided to do it. Then during the script party, I explained to everyone else what the original was, what we'd changed it to and why, and at that point anyone was able to weigh in. As a team, we decided it was a good fit and went with it.
In terms of name spellings, that's a general style rule we have at NISA (there are basically several accepted ways of Romanizing Japanese names, and we use the one we feel best fits our localization style).
The amount of direct translation experience varies, but all of our translators are native Japanese and English speakers and are familiar with the medium, so their grammar and vocabulary is there.
I can't speak for other companies, but for us the developer has final say in all of our changes. Sometimes we'll suggest a change that they're not a fan of, and we'll lay out exactly why we think it's a good change. Sometimes they agree and we make the change, sometimes they don't and we keep it how they want it. Either way, the developer is always part of the process and ultimately they have the final say. (Which has worked out flawlessly for us so far.)