You should definitely post some info about your project to tex4ht mailing list, I hope some interesting and more informed discussion might happen there.
you may also take a look at make4ht (https://github.com/michal-h21/make4ht), it is a build tool for tex4ht, included in TeX distributions and it also solve some of the problems as your script (ligatures, spurious span elements, image conversion, unicode, etc.). It can execute custom commands on all output files, so your script could be used with it as well
you may also take a look at make4ht (https://github.com/michal-h21/make4ht), it is a build tool for tex4ht, included in TeX distributions and it also solve some of the problems as your script (ligatures, spurious span elements, image conversion, unicode, etc.). It can execute custom commands on all output files, so your script could be used with it as well