Polish translation

Very cool! If you have a GitHub account you should be able to create a request for adding them to the languages folder. If not, that is OK too, you can package the .po and .mo files in a Zip file and upload it to this forum post, and I'll add it to the code.

If you're interested we've created a documentation page that describes how you can easily add and make changes to existing translations etc. through GitHub: Adding content type translations via GitHub 
(making the changes through GitHub makes it a lot easier for us to review and then add them to the code)

Thank you!

It appears the editor translation was missing a couple of commas(,). I fixed that and added the translation to the official editor. It should work if you download and test it: pl.js
You may use the edit button to make further changes if required. The translation will be part of the next release of the plugin.

Regarding the custom editors, like the Course Presentation tool, they have a separate file in their own repo. E.g. The Course Presentation Editor's translations are found here, while the Interactive Video Editor's translations are found here.

I don't speak Polish very well and most of the translations for the WordPress plugin looks fine when I check against Google Translate, however, there are a couple of translations I'm curious about:
1. H5P Content is translated into Advanced Presentations.
2. Libraries is translated into Templates.
3. Results is translated into Activity.

It sounds to me like these words have been adapted to fit a certain site or scenario. When translating it's important that the meaning of the words do not change. If someone were to come and ask for help with Advanced Presentations no one would understand that they actually meant H5P Content.
If we are going to add the translation to the official H5P Plugin you must make sure that there are only translations and no adaptations.

If you think that the word should be changed it must be changed for all translations. To do this please create another forum post and argue why that word is a better fit than the current.

Again, thank you for your contribution!