as long as the text is PD for the US, you can use it. The Gutenberg text is ok to use. I would be careful with wikisource texts, unless there is a scan included, but it's best to take the Gutenberg text.
The grandson doesn't enter into public domain discussions. For Europeans we need to make sure the author has been dead for 70 years (which he has in Eminescu's case), but since you are living in the US, that is not a problem for you either.
Looking forward to hearing your poem Good luck with your first official LV recording. You can find all the details about correct filenaming and how to say the intro and outro in the first post