Sorry I did not see this yesterday. PR is not a great tool for this.
I would use a third party app (SubtitleEdit is my favorite).
I just walked through a try at this.
In the Word document, remove any lines that are not to be created as captions.
Save As -> plain text. (I specified ending lines with CR/LF, but this may be automatic.)
In SubtitleEdit (SE), File -> Import plain text. (Pick your .txt file.)
In the window that opens, I left it as "Auto split text." There are a number of options. I also left the defaults, including single line max length of 42. "Generate time codes" allows specifying if you want a gap between captions or one right after another. I would experiment with these based on your material.
You can pull a version of your video into SE and adjust timing there.
Then export .srt. If you are burning in, just bring into PR and make final adjustments there. If your end product are sidecar files, you may be able to use the ones from SE.