Ven. Maria de Agreda's Mystical City of God is more reliable, albeit still private revelation, I would go with her account over Emmerich. Although I still like Emmerich's books.
There are def problems with her writing, it was condemned by Pope Urban VIII in 1625, the congregation of the inquisition in 1681 and Innocent XI forbid it from being read. Then the censure was confirmed after a more careful thirty-two session study of Croset's translation. Only thing going for it is that the decree of Innocent XI was suspended for whatever reason, but only in Spain. Any further requests to suspend the decree was ignored.
Either way, the book is obviously suspect. If something getting that much censure and kicking up controversy amongst theologians isn't suspect then I don't know what is. The statements which the reports present on the Catholic Encyclopedia are pretty sketchy to say the least. I'm not sure I would call it safe by any means like how one may call "The Imitation of Christ" by Kempis safe.
https://www.newadvent.org/cathen/01229a.htm