You could temporarily add the English language to your project and then use the Batch Translate feature to translate from English to Dutch:
Alternatively, instead of using Batch Translate in step 2 and 3, you can just open the relevant forms and microflows and edit the captions directly. Set your language to 'Dutch', and English captions will appear within angle brackets ( <Like this> ) where there is no Dutch translation yet. For this to work, you have to set English as default language in the project settings.
Language operations > copy > from english to dutch for module LDAP