How to know if my file is inserted correctly `glyphtounicode`

In several suggestions for making pdflatex output copy-and-pasteable, is part of the suggestion to insert the code,

\input glyphtounicode.tex\pdfgentounicode=1\pdfcompresslevel=0

TeXstudio marks in red that this file glyphtounicode does not exist in my .tex document directory. But I found the file in the MikTex directory. My question is, how do I really know that the file is being inserted?

In addition, I also insert the following code,

\usepackage[a-2b,mathxmp]{pdfx}[2018/12/22]\InputIfFileExists{glyphtounicode-cmr.tex}{}{} \InputIfFileExists{glyphtounicode-ntx.tex}{}{}

The glyphtounicode- files are in the pdfx package folder, are they also being inserted correctly?

Additional information: I'm using pdflatex on TeXstudio on Windows.