There are several issues with your configuration. Fist of all, in testpkg.4ht:
The original \SectionTitleTest takes one argument, but you redefine it as argument free. Because of this, all content of the configuration is inserted before the text you pass as ...
A substantial lwarp example is here: this is a 65 page set of lecture notes for a course I teach. It includes tikz graphics, cleveref references and a lot of maths. I had to supply some js and css to tweak the final output but lwarp did all the heavy lifting.
I have tried latexml on the same document but couldn't get cleveref to work.
It seems that MikTeX version of TeX4ht is not up-to date. It can happen as TeX4ht is installed directly to TeX Live, the updates are not installed on CTAN, so MikTeX maintainer are not notified of updates. I've made a request on MikTeX issue tracker for the update, so these issues will be hopefully fixed soon.
In the meantime, we can fix your issues using ...