Hi,
The focus keywords are not translatable since they are only part of the back-end side of your site. Translating those won’t impact your ranking in any way. What’s important to translate is the meta-information: titles, URLs, and meta description — content that is actually visible to the visitors be it on the website itself, or in Google search results.
The major purpose of using focus keywords is to help you create content around them. Those are used internally by SEO plugins to score your page content in accordance with that term/keyword.
This doesn’t mean that you shouldn’t use focus keywords with your SEO plugin of choice when manually writing your source text. This way, the SEO plugin can guide you through optimizing that page for a specific term so it ranks better in your default language. However, when TranslatePress translates your content in the additional language, the keywords that are present in your source text will be translated anyway, so you won’t need your SEO plugin’s guidance to rank in the translated languages. The translated content (that is visible to the visitors) will basically have the same focus keywords throughout the page as the source, just in a different language.
