Many localization services / Translation Management Systems (TMS) (like those listed) or developer tools (Lokalize, Phrase, etc.) tack on l10n as a layer at the very end (after development). Especially with these 3rd party contractor tools, a lot of the time the l10n happens without context of the design / product -- they just translate the strings that exist in production.

At the moment, we've seen teams in Ditto use it as a localization solution if they already localize their mockups. However, we are hoping to support this more fully in the very near feature with the ability to create variants of text in mockups in Ditto (think languages, states, etc.)

Localization is definitely a pretty big pain point for teams, but we've seen teams struggle to coordinate copy from draft to design to development, even in their primary language.