Any recommendations for a PDF editor? I’ve been using LibreOffice Draw, but it doesn’t seem to preserve all the formatting/positioning.
Xournalpp is what you are looking for.
It has a horrible outdated interface, but it makes layerwise edits and preserves the original data of the doc.
Unfortunately not open source, but I have good experience with Master pdf Editor. It “is a proprietary application to edit PDF documents on Linux, Windows and macOS. It can create, edit (insert text or images), annotate, view, encrypt, and sign PDF documents.”: https://www.linuxuprising.com/2019/04/download-master-pdf-editor-4-for-linux.html
+1 for master PDF editor. It’s the only one that I found working. There are 2 version: one completely free (V4) and one with subscription (V5)