Which software converts academic publications from PDF to Word without mangling complex formatting?
UPDATE: The question has gone through 10+ revisions since I wrote this answer. I haven't checked to see whether it is still relevant. I'll try to respond to comments.
I'll start by disclaiming: My initial solutions do not follow the prescribed pdf to doc conversion (whilst my last solution does, albeit, it's probably a bad solution), and I haven't tested them, which violates the OP's constraints. I disregard these constraints because I don't think they are particularly relevant.
It isn't clear whether on-screen, digital reading or printed, physical reading is preferred, nor how much adjustment in text size is desired, clarification may allow more focus.
The trivial, obvious solutions, which have surely been tried, are: Large screen plus zoom and printing to a larger paper size, e.g., A3 or A2 (the former being more commonly available), rather than A4. Annotations and highlighting can be applied to pdfs with numerous tools.
For various other enhancements, numerous tools exist on Linux, which can be scripted to suit needs. For instance, a page could be split into smaller parts and manipulated in various ways, e.g., split a portrait page into top- and bottom-parts, and blow up each part onto a horizontal page (optionally of larger size). All operations can be automated. This approach cannot fail particularly badly for academic papers. At worst, perhaps the split is applied in the wrong place, but, the two parts can be displayed simultaneously, aligned at the lower/upper edge, or by folding the top edge of a printed page.
Linux tools can also be used to convert to word processor format, for instance, pdf2ps and ps2txt can be combined to convert pdf to plaintext, which any word processor can open. (This is my worst solution. I doubt tables, footnotes, formulae, etc. will be handled particularly well.)
Converting to a word processor format seems like a misdirection. That's why my last solution probably won't work. Extracting another format from a pdf seemingly goes against the design goal of the pdf format, namely, to present documents in a [software independent] manner...encapsulat[ing, in each file,] a complete description of a fixed-layout flat document, including the text, fonts, vector graphics, raster images and other information needed to display it (source: Wikipedia).
My apologies if I'm way off mark here. I'm unsure of your precise requirements.