Right now, drush kw-it will import translations from enabled modules, but can't it parse the makefile and import from there? It'd make it easier to add the po files to the repo, something useful for distribution and install profiles development.
Hmm, I'm not sure what your suggestion exactly is. You can supply translations = nl in the make file and the Drush Make will already download the correct PO files.
translations = nl
that's what I needed, thanks ✌️
Great. Then I'll mark this as a question and close it.