The question is about extracting certain HTML elements, out of a given HTML file. There are multiple ways to do this. Let me point out some of them below.
1) Use a script with a Library to do this. For Java use JSOUP.
String br = "<html><source>foo bar bar</source></html>";
Document doc = Jsoup.parse(br, "", Parser.xmlParser());
for (Element sentence : doc.getElementsByTag("source"))
System.out.println(sentence.text());
}
This will give you the list of elements with the HTML tag source. You can do the same for other languages like python (use BeautifulSoup) and NodeJS.
2) You can write a script to read HTML files as text files and do a search on text.
Move all your HTML files into a folder, and write a small program to load each file and search for the specific tags. Later save it to a CSV or any preferred output.
3) You can do the same with grep.
Simple do a search and load the results directly into a CSV file.
There are multiple other ways to do it. Since you mentioned that the manual workload is higher, try doing a small script to get the job done. Use the first approach as it is faster and easier.