Back in late 90's and early 00's, I was involved with many projects on US farm going to Japan market. Amazon.com, L.L. Beans, Ask.com, and so on. All of these big boys used specialized translation service farms. The issue is the translators, especially when the product is not released to the public yet, don't know the context of each words where it appears. English word can be less specific than Asian one. Sentence styles also matters depending on where and how they appear.
While I have never been a professional translator nor received any kind of training, I prefer translating UI by UI. I know this is inefficient.
This is how I have been doing on my spare time :-)https://docs.openclinica.com/3.1/technical-documents/openclinica-and-internationalization/recommended_steps