How to overwrite dutch translation

You can contribute to translations here: https://translate.www.ads-software.com/projects/wp-plugins/my-tickets

Once a language reaches 100% there, I’ll remove any existing translation from the plug-in, so that the www.ads-software.com version takes precedence.

I suggested for all the lines (Dutch) new translations. Is this ok? Or not?

Yes, that’s fine. Somebody in the Dutch language community will eventually go in to review and approve your suggested translations. (I don’t have any direct power to influence that.)