Here's a small basic tool from my end to help you export all tables in a webpage to an XLSX (observable in DOM) using Sheet.js.
Feel free to use it!
If CSP blocks the script, manually include the cdn.sheetjs.com/xlsx-0.20.3/package/dist/xlsx.full.min.js script in your browser and re-try the html-tables-to-xlsx plugin.
Feel free to mod it according to your needs.