We use Phraseapp for all text strings in our app. Mostly we, designers, are the one responsible for main (English) copy, but we're not native, so we're supported by the content/marketing team if we're not sure about some stuff. The caveat of working with marketing people is that sometimes they don't get how UI copy should tell users the message in the most concise way. Translations are handled by external people, I'm not really involved in this process.
We use Phraseapp for all text strings in our app. Mostly we, designers, are the one responsible for main (English) copy, but we're not native, so we're supported by the content/marketing team if we're not sure about some stuff. The caveat of working with marketing people is that sometimes they don't get how UI copy should tell users the message in the most concise way. Translations are handled by external people, I'm not really involved in this process.