It's quite easy to use MathJax as a preprocessor, it will happily read your MathML and convert it into SVG.
For example, to convert your example to PDF in Linux, I did:
sudo apt install npm
sudo npm install -g mathjax-node-page
wget -O test.html \
https://www.princexml.com/forum/post/22573/attachment/test1%281%29.html
mjpage < test.html > test-with-svg.html
prince test-with-svg.html
The first two lines install the "npm" package manager and the "mathjax" package.
The "wget" command fetches your example.
The magic happens in the next line, when "mjpage" converts the MathML markup in the HTML file to SVG.
In the last line, Prince happily converts the resulting HTML/SVG code into PDF.
test-with-svg.html 13.9 kB test-with-svg.pdf 24.8 kB
Edited 22 Jan 2021 by howcome