I have translated all WPMU DEV products and here are the common issues to fix:
1. But there are still many Strings that do not display translations, its related to multiple text domains not getting handled correctly
2. Especially the Wizard start section always does not display translations (This is very bad for beginners)
3. It is recommended to move Strings from Development (trunk) to Stable (latest release) because WordPress only synchronizes translations in Stable (latest release)
4. With embedded Plugins like Integrated Video Tutorials, please note: WordPress will automatically take the code with the translation, which will break the embedded interface. This is the feedback that “Independent Analytics” also encountered “WordPress is taking the translated version of the word “Analytics” and using it in the code: https://d.pr/i/KuIlC4. It really shouldn’t be doing that because it makes the CSS class unusable.
Hope these help you develop better translations for your Plugin, Help reach more global customers.