Hi David Gopois,
You can export all comments into an *.xfdf file.
1. Open your pdf > Open the 'Comment' section (upper right corner) > Press the button I can't describe... er... When you hover your mouse over it, it reads 'Options', it is the rightmost button with upside down triangle denoting a drop-down menu, in the same line with the 'Find' entry field> From dropdown menu, select Export All to Data File > Save it as XFDF (NOT fdf which is by default) in the same folder as original pdf.
2. Download and then unzip this XFDF file-type zip: drive.google.com/open
3. Create a project clearly stating its purpose. For example, I named it 'XFDF_en-ru' (for me to know that this project is only for pdf comments, English to Russian). Go to Project Settings > File Types > Import Settings... > Import the XFDF_filetype.sdlftsettings from the above-mentioned zip archive. Remove all file type ticks except for SDL XLIFF (actually you cannot uncheck it even if you try) and 'xfdf' (it may read 'xfdf2' - if so, it is still ok). Click OK. Your project for PDF comments is ready.
*** I do not create another project each next time but just remove my file(s) once a week or as soon as I consider them clogging my list of files, then I add new ones. This will save time for me.
4. Add the xfdf file and translate it. Once you are done with your translation, save it normally (Save Target As). Run the newly saved xfdf. This will cause your pdf to open with translated comments.