How to change a font in a PDF, a single glyph renders wrong (PDF created using Adobe Acrobat Pro XI,

I have a document that was created from a scanned document, after using the Acrobat XI pro's text recognition tool, with parameters language: Spanish; PDF output: clear scan; downsample to 600 dpi.

It worked rather well, with only small problems, which can be easily overlooked. Except that I use foxit PDF reader to actually read PDF (I have a slow PC), and there is an "a" glyph that in Adobe looks normal, but in foxit it looks filled, without the empty space at its center (the problem exists only in italics lowercase "a") (example of problem). There are lots of lower case italics a's, almost in every other page. I use this book to study for a central course for my degree, it's the best we have at our school's library in Spanish, so I read it almost every day, and it's quite annoying (example 2).

There are examples of that italics lowercase "a" that show up fine in foxit the a's in "plantación" are normal.

Sample pages, the first page has normal a's, the second has filled a'saccountancyservices

Could I copy the normal looking a glyph and replace the one that causes the problem? if so, what software would I need?

Thanks for reading this.