Open source program to modify PDF text: is pdf4qt the answer?

This is the only hole in my open source software. I use Master PDF Editor to edit PDF text, and it works great, but is proprietary.

Has anyone tried pdf4qt (https://github.com/JakubMelka/PDF4QT)? Can it modify existing text on a PDF? I haven't tried it because it is not in the Ubuntu repositories, although it does have a Flatpack.

Is there any open source program I'm missing?

Note that I'm talking about modifying existing text. I'm not talking about "editors" in the sense of merging PDFs, or annotating them (which Okular and Xournal do a great job of but from what I understand cannot modify text). I'm also not talking about importing a PDF (I think Libre Office can do this?) because it can change a lot how the PDF looks.